Addressing the Climate in Modern Age's Construction History

Compulsory schooling in some Italian States, especially in the Duchy of Milan, dated back to the end of the eighteenth century. Following the legislative proposal submitted by Minister Michele Coppino, compulsory schooling in the whole new kingdom of Italy initiated instead only around 1877, over 16 years later than the unification. Even if the Italian State funding were low, they nevertheless encouraged the construction of new school buildings and imposed new standards. Italian architects showed a great interest in the topic and develop new solutions, sometimes inspired by current European experimentations and publications.Architect Camillo Boito built two schools, both in Padua (1877–80) and Milan (1886–1890), which represented a concrete example of his idea of a new and “national” architecture. Up-to-date construction techniques were developed and thermal comfort was also improved, according to the standards of that period. The centralized heating systems adopted in the two school buildings testified to the fast development of industry, particularly in Milan, which become the most important Italian center in the sector.

In terms of quantity, rural schools were certainly at the heart of the problem; indeed, in the small towns and in the cities of Catholic countries, after the abolition of religious orders and brotherhoods, the ample spaces of monasteries and the halls of the confraternities could be assigned to the education. France had precociously decreed compulsory and free primary education in 1793, only to quickly abandon it. In the Habsburg States, as early as the final years of the reign of Joseph II (in Milan in 1788), the matter proceeded with great difficulty yet did not founder: a kind of construction manual, Koller's Der Praktische Baubeamter, presented not only models for rural schools but also a regulatory framework (Koller 1800). 2 Certain characteristics relating to health were already emerging: lighting of desks had to be from left to right. With the advance of industrialisation, school buildings as a building type, in terms of their overall function and educational impact, as a design topic, took on particular importance. The regional imbalances increased with the industrial take-off, and combined with the population increase; re-use of existing buildings no longer sufficed and, with new buildings now considered indispensable, specific standards were progressively defined ( Fig. 1). Fig. 1 School of ten classrooms ("Edifizi di dieci aule, planimetrie"), Bongioannini (1879), tav. 2 2 pp. [39][40][41]II part,pp. 410,[458][459][460][461] A. Grimoldi and A. G. Landi From 1851, the World Fairs, whose purposes included education, dedicated specific spaces to school buildings. Legislation reinforced public schooling and, after a century of attempts, mandatory primary education began to be effectively translated into practice and its duration was increased to three years. The education laws of the German States, that of the Habsburg Empire of 1869, the Education Act of 1870 in England and 1872 in Scotland and the laws of 1877 in Italy and 1882 in France boosted significant building activity and gave rise to regulations governing it. Specific bibliography on school building health grew notably, and crossed citations became numerous.
An overview of the history of Italian school building was still lacking, while literature on schools as an institution and on teaching was extensive although uneven. However, the previously-mentioned bibliography at European level, together with certain fortuitous circumstances, permitted, between the Italian Unification and the end of the nineteenth century, an overall vision of one particular aspect: climate control within schools. In this sense, the general concept of the buildings was still more determining. Subsequently, after the first world war, ventilation would become a secondary exigence in reference to the new medical guidelines, and the industrial take-off and diffusion of electric motors would reduce the bulk of installations, entrusting ambient balance to them.

School Legislation in Italy After the Unification and the Birth of Regulations on School Buildings
The Casati Law (1859) required municipalities to institute and finance the first two years of primary education in all areas where there were at least fifty children, but subordinated this to the requirements of the population, as determined by the municipal councils. In 1877, Education Minister Michele Coppino reduced compliance to one school per municipality, but made it possible for the Government to substitute for the defaulting municipalities at their expense. In return, he provided meagre financial support; indeed, Law no. 4460 of 18/07/1878 granted municipalities the faculty to contract loans of up to thirty years with the Italian Deposits and Loans Fund-in part with interest limited to 2%, thanks to the State's contributionfor building or repair of school buildings. This Law limited the interest burden on the Italian Ministry of Public Education to 50,000 lire per year. This assistance consisted, more than anything, of the offer of sufficiently ample long-term funding at a reduced cost (De Fort 1979), 3 but had limited results (Fig. 2). The implementing regulation 4 defined the first brief guidelines on building choices. The substantial reiteration of these contributions at the end of the decade 5  was accompanied by more detailed instructions. 6 The new century began with a further reiteration, 7 together with new regulations. This sequence of events shaped increasingly detailed regulations on school buildings, 8 the three pages and 13 articles of 1888 became five pages and 18 articles in 1901. The relationship of these with buildings, constructed or merely designed and published, was two-fold. The "instructions" adopted the introduction of certain advanced solutions which had emerged during the previous decade, and their enactment was also notable in parallel changes to some standard dimensions or solutions. Overall, rapid technical progress was perceivable together with a change in expectations and attitudes. For instance, in 1888, the required artificial lighting consisted of lamps situated at least 1.5 m from the students' heads. Where electric lighting is not used, oil, petroleum or gas burners should be chosen. Where gas lighting was adopted, the application of combustion product waste pipes was recommended. In 1901, an entire article recommended the use of incandescent electric lighting. If it was Fig. 2 Construction details, including the heating system ("Dettagli di costruzione"), Bongioannini (1879), tav. 21 necessary to resort to gaslight, each lamp should be fitted with incandescent mantles. Electric lighting quickly spread in the major cities, where the demand for new schools was highest, while energy transmission made it increasingly widespread. Gas lighting, dependent on supply networks, was used in a limited number of urban centres and, in 1901, only its most advanced and low-consumption formthe Auer von Welsbach gas mantle, patented in 1876-merited the regulation drafter's attention.
However, rural schools kept using oil (or petroleum) lamps with glass flues ("waste pipes"), despite the alternative of "combustible gas" (namely acetylene) proposed by the regulation of 1901.

The Museum of Teaching and Education
In reality, as would occur the following year with regard to financing, Coppino rationalised or developed earlier initiatives and brought them to fruition. These were the projects of former Education Ministers Cesare Correnti (1872) and Antonio Scialoja (1873). The need for improvement in the quality of education was generally felt and Ruggiero Bonghi, 9 Minister of Public Education from September 1874 to 1876, founded the Museum of Teaching and Education 10 in 1874 with this objective. Following a trend that was spreading throughout Europe (Tauro 1903 11 ;Cossetto 1997), this Museum gathered information and educational materials, from books to wide-ranging objects, in the service of that teaching by means of things, "objective lessons", models or samples, that distinguished the nineteenth-century education. The Museum aimed to become a reference point for the schools of the Kingdom of Italy, and for this objective published its own journal (Sanzo 2017 12 ). Bonghi announced the programme in his report on the Vienna World Fair in 1873 (Bonghi 1873 13 ), and the same book featured a report on architecture by the architect Camillo Boito (Boito 1873 14 ). School buildings, naturally, formed alimited but essential-part of this programme. 9 From 1866 to 1874 he was editor of the Milanese daily newspaper La Perseveranza, which published some essays of the architect Camillo Boito [from 1860 to 1865, according to the list of his publications in s.a., Boito (1916, pp. 176-205)]. 10 Regio Decreto 15/11/1874 no. 2212, published by Tauro (1903, pp. 9-10). The most relevant documents on the foundation and the live of the Museum life are collected by Sanzo (2012b). Concerning the object of this paper, a nearly contemporary and already mentioned witness, Giacomo Tauro and his work, is very useful. For a more overall perspective Sanzo (2012a) and also Meda (2010 Through a Ministerial Decree of 30/12/1875, Bonghi established the commissions that would oversee the Museum's activities, including the one for school building design, composed of a doctor (Angelo Scarenzio), an agronomist (Fausto Sestini) and two engineer/architects (Francesco Bongioannini and Giulio de Angelis). The latter is very well-known, being among Rome's most original late nineteenth-century architects and, at that time, he had just designed a villa in Rome for the Minister Bonghi (Zullo 2005 15 ); after a successful professional career, he returned to public employment in 1895, as Director of Lazio's Monuments Department (Zullo 2005 16 ;Miano 1987).

Francesco Bongioannini
The former had been an inspection engineer at the Soprintendenza archeologica of Rome from 1872 (La Rosa 2011 17 ; Scavi 1872 18 ) and, when this was closed, in 1875, he entered the newly-established Direzione Centrale per gli Scavi e i Musei (Melis Tosatti 2005 19 ) in the capacity of topographical engineer; the following year (La Rosa 2011 20 ) he became General Inspector for Architecture, preferred to Giulio de Angelis.
In this way, he moved into the "Divisione 2a" which, from 1877, assumed the name Provveditorato alle Arti of the Ministry of Public Education, directed by Giulio Rezasco (La Rosa 2011 21 ). When the Provveditorato and the Direzione Centrale per gli Scavi e i Musei were merged by the Minister Guido Baccelli, in 1881, Bongioannini continued his work and, when in 1887 the direction was structured in three sections he assumed directorship of the "Divisione II", with responsibility for conservation of monuments (Melis Tosatti 1999 22 ). After the restructuring ordered by Minister Pasquale Villari, in 1891, Guido Baccelli, returning as Minister in 1895, partially re-established the status quo but Bongioannini returned to Turin as superintendent of schools (L'osservatore scolastico 1896 23 ), and, at the end of his career, was transferred to Alessandria, in the Piedmont region (I diritti della Scuola 1908 24 ). He can again devote himself to the school buildings (Bongioannini 1898).
Bongioannini's role at the Ministry of Public Education made him the immediate administrative reference person for Camillo Boito, a member of the Giunta Superiore di Belle Arti since 1879. This relationship may be deduced from the murky and inglorious affair of the destruction of the Church of San Giovanni in Conca, in Milan, an obstacle to the straight stretch of the new via Carlo Alberto, in which the two cooperated to promote the City Council's demolition intentions (Colombo 2005 25 ).
This singularly close relationship between the debate on school buildings and the care of monuments is of little wonder: both competences were centralised in a single ministry, often managed with equal interest by a single minister, pointing more to a network of personal relationships than to a continuity and sharing of concepts.
Bongioannini's texts place greater emphasis on the topics of education, although their titles are, at times, deceptive. The multiplicity-to the point of confusion-of his interests and their interweaving with his administrative activity are typical of that century, thanks to a population curve that quickly led to positions of responsibility. Fluctuation between utopia and mania and between egocentricity and social commitment are characteristic of the nineteenth century, meaning that both actions and texts should only be assessed with close reference to their context, taking no account of the different meanings that words and phrases may subsequently have assumed later. Another great and polyhedric bureaucrat of that era, Carlo Alberto Pisani Dossi (Melis 1996 26 ;Serra 1987), depicted this environment and these tendencies-linking society and architecture-in a famous pamphlet dedicated to the "madmen" in the competition for design of the national monument to Vittorio Emanuele II in Rome, called "Vittoriano" (Pisani Dossi 1884). The tone he adopted -exasperatedly grotesque-highlights the tendencies and characteristics of an era, which permeated its daily life but in that dimension they appear attenuated as with inactivated vaccines.
Bongioannini dedicated his engineering degree thesis to heating (Bongioannini 1870), another key theme in the problems discussed here, and initially he planned to base his professional identity on these issues. The habit, that time, of the Scuola di applicazione per gli Ingegneri in Turin, of presenting degree theses as printed pamphlets made his brief essay easily accessible. In Rome, the Piedmontese origin -or the exile to Turin between 1848 and 1859-of a significant portion of the higher bureaucratic levels, provided the young engineer with a promising network of relationships, and his sufficiently generalist technical expertise permitted him to meet a varied demand. He was able to achieve the drainage of waters in the Roman Forum, in order to resume excavations (Scavi 1872), but also to design the layout for the arrangement of the Collegio Romano as Roman seat of the National Library, one of Ruggiero Bonghi's priorities. only partially-existing structure. Any revival or adaptation of Renaissance themes to new proportions and requirements, so widespread in the Rome of his day, is distant, and this anomaly also attracted Paolo Portoghesi, now sixty years ago (Portoghesi s.d. 28 ). While unable to establish its paternity, he connected it to a limited but significant group of buildings which could refer to similar cultural roots. The search for an unconventional "new style", from a "rationalist" perspective, as a pure construction, was not rare in the Piedmont region, particularly for explicitly utilitarian programmes.
At the Scuola di Applicazione per gli Ingegneri in Turin, when Bongioannini was a student and showed especial interest in industrial engineering, the professor in architecture was Carlo Promis (Savorra 2017), who also held the equivalent chair at the city's Accademia. He was substituted for just one year (1870) by count Carlo Ceppi, and then he leaved the post to Giovanni Castellazzi (Richelmy 1872;Pugno 1959;Vitulo 1993 29 ), who proclaimed himself a student of Promis'. Also decisive in the field of construction, particularly in road-and railway-building, was the influence of Giovanni Curioni, teacher in different positions, from 1863, and repeatedly indicated as the effective Department Head.

A Model for Municipalities
In his illustrated book on schools (Bongioannini 1879) Bongioannini adopted the same architectural language. The activities of the Museum of Teaching and Education included annual conferences and, during those of 1876 and 1878, the first issue "school desks and houses" was presented respectively by Girolamo Buonazia, professor of Applied Mathematics at Florence's Istituto Tecnico and Accademia di Belle Arti, and by Antonio Labriola, the Museum's own Director (Tauro 1903 30 ). The Secretary General, Martino Speciale, a lawyer and long-time member of Parliament-called upon to ensure the continuity of a ministry in which, due to the frequent government crises, Francesco Paolo Perez and De Santis succeeded Coppino-responded to the dedication to the Minister, a generic "His Excellency": he requested to provide two hundred copies to the Ministry, so that the book "may be made known to the provincial school authorities". He referred to an old eighteenth-century custom according to which the dedication corresponded to a purchase of copies, here pre-arranged within the same offices.
The types of buildings for primary schools (Fig. 1) who, in turn, loved the regularity of Turin (Szambien 1984 31 ). Another reference to the teaching of the École Polytechnique is the division of buildings into modular elements, in this case the classroom with the vestibule. These, in turn, may be broken down into single square modules. With their porticoes in place of corridors, which were reserved-although it is not known how-for the harshest climates, sequences of columns and over-abundant distribution, arranged according to the same modularity, these school buildings were presented as a model of "rational composition" which would also give rise to "rational constructions". Composition and construction were originated by the function, in a programme combining traditional reflections on the choice of area with the most binding quantitative, regulatory and sanitary specifications of compulsory schooling. This approach involved "seeking, in all their essence, the most important monumental buildings, attempting to understand the ideas that shaped them … repeating, on each of them, all the workings of the mind that created them" (Bongioannini 1879 32 ). The principles of Viollet-le-Duc expressed the great-and contradictory-desire of that century, namely progress freely built on the nation's past and individuality. Referring to these, Bongioannini sought to provide school buildings with the necessary link to history as well as the essential didactic dimension. Rational construction aimed to emphasise the regular stone or brick load-bearing structure, clearly distinguished from "infills", like Gothic and even "Lombardesque buildings" (Bongioannini 1879 33 ), a further, generic, filius temporis homage to the myth of the rationality of medieval construction. Of course, "the decorative parts are not achieved through superfetation but by embellishment and ornamentation of the constructional parts, while, for the classrooms, successive… openings in the form of a continuous window … are envisaged … divided only by pillars or small columns" (Bongioannini 1879 34 ). The text, often confused and redundant, particularly in its historical excursus, conceived-it would seem-in homage to the principle "repetita iuvant", shows via which humble, involuntary routes, that Kaufmann would never have imagined, it is possible to slowly advance on the path "von Ledoux bis Le Corbusier". It is therefore advisable to focus on building health and trace another stage in the development of standards. The seventy student classrooms stated in the Regio Decreto no. 4684 were limited to fifty students, each of whom were entitled to a volume, corresponding to the height, of five or six metres, depending on the clemency of the climate; 13-15 mq were also added for the teacher. The air had to be renewed two or three times per hour, and the glazed surfaces-1.5 m above the ground, in order to render them inaccessible to children -had to be a minimum of 1  (Fig. 2). The fireplace was fed by "stale" air, which entered via a vent opened at the level of the classroom floor and exited as smoke via the chimney flue. Instead, fresh air entered via the grates to the sides of the stove, flowed around the stove and in a large flue within the wall thickness, surrounding the iron smoke flue, and warmed up exited in the classroom, just below the ceiling. References to use of this equipment as a summer ventilation system, activated by a flame of obviously reduced intensity, perhaps limited to a gas or acetylene burner, are unconvincing. The teacher played a key role, being able to open the window transoms and operate the external tiltable shutters ("cord shutters") or "Chinese-style shades", consisting of thin, fixed, wooden battens, and the internal blinds in order to protect preferably south-facing rooms from solar radiation. Bongioannini made little use of the notions exhibited ten years earlier; indeed, these guidelines and tools for climate control appear incoherent and, above all, vague, as though the interest of users and the ability of the municipalities to apply them were very scarce.

Camillo Boito and the Schools of Padua at the Reggia Carrarese
The primary school designed by Camillo Boito for the city of Padua briefly pre-empted the first two stages of the regulations about the school building. This was, perhaps, no coincidence: he succeeded in skilfully presenting his work as an example in the official spheres and broadcasting it to the public of technicians and administrators, and was able to obtain resources far superior to those granted to other architects. The documentation demonstrates that his buildings were carefully considered and, to varying extents, imitated. The reports and articles illustrating them and the publications citing them also offer a broad picture of the European literature of the subject and therefore of the references known to the technicians and educated Italian public of the period, which, indeed, were promptly reflected in constructions. In fact, they set the standards for more complex school buildings, also in terms of well-being and installations (Figs. 3,4 and 5) In Padua, Boito won the assignment on 6th March 1877, and the building was inaugurated at the end of September 1880 (Serena 2000; Vettori Ardinghi 2012). The Minister Coppino had presented his bill on compulsory schooling to the Chamber on 9th February (Talamo 1983), and the law was approved on 6th July of the same year. In this singular interweaving of dates, the Padua initiative would seem to suggest tangible political support for a Minister, Coppino, who was in a broader sense, man of culture, active not only in the education problems but also in the issues of monument care. He proposed a bill on the subject to the Senate on 3rd February 1877 (Nicolini and Sicoli 1978 35 ). In 1888, his subsequent proposal, already approved by the Chamber, was rejected by the Senate by secret ballot (Bencivenni et al. 1992

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A. Grimoldi and A. G. Landi Coppino (Zucconi 1997 36 ). In his report of 29th August 1877, Boito repeatedly cited the work of the Commission established by Bonghi, particularly when he claimed not to adhere to its guidelines. His building comprised three storeys, in contrast to the prescribed two, and his orientation draws the greatest possible benefit from the area, as is essential when situated within the urban fabric of an historic city. The "large, comfortable, well-lit […] 5-m-high classrooms housed less than 70 students for the first and second classes and approximately 40 for the third and fourth class. The windows were separated by "very narrow piers in order to avoid shadows", with sills 1.5 m above the ground, and their surface area was between a quarter and a fifth of that of the rooms, equal to 70 m 2 . The plan for heating and ventilation was more complex: the Commission "elected by the Council", which followed the project from its origins, did not always agree with Boito's proposals. He had to renounce the vents at the base of the walls, under the windows, for "eradicating the impure air of the lower layers". The squares, clearly visible in the design drawings, disappeared in the subsequent engravings. Ventilation was provided by the window transoms, which were quadripartite in order for the panels to fold into the wall thickness. Heating, to be "artificial, even on the harshest winter days", was opposed by the Commission, for "extremely serious reasons", namely the running costs which would be borne annually by the Municipality and, consequently, by the tax-paying citizens. Hostility towards mandatory schooling itself was rife among the influential figures of the Lombardia and Veneto regions, and the gaps in the Casati Law were an advantage not secondary to National Unity… With the exclusion of individual stoves and "hot water heaters, extremely costly to install and maintain", air heaters "which do not cost much and are easy to repair" were suitable for providing 12-13°C, but 8°C or 9°C would have sufficed in the new school (Fig. 8). Boito succeeded, at least, in enforcing the installation of "horizontal pipes between the floor and vaults, and vertical ones in the walls". While somewhat unclear, this phrase recalls a proposal by Rinaldo Ferrini-a colleague at the Politecnico-who contemplated, for schools, the circulation of hot air under the November 1879-among the other alterations which significantly increased the estimated cost of 265,000 lire-a contract was entered into with Giuseppe Pollino for the construction and installation of two heaters at the "greatest possible reduction on the forecasted 5200 lire. The heater vent covers throughout the establishment must be made from brass". This was the most widespread solution at the time in dwellings, with vents at the base of the walls (Curioni 1873 38 ; Sacchi 1874 39 ). Among the drafters of the most diffuse manuals, Curioni, in particular, appears to have been a promoter of natural circulation, introducing clean air from below and removing it from above. Sacchi varied according to the circumstances, and appears to have preferred inverted circulation for very crowded environments. Ferrini also, opted for this solution: that appears contradictory. He was familiar with the work of Reid at the House of Parliament (Ferrini 1876 40 ) and used the illustrations from his treatise in which natural circulation is increased using extractor chimneys (Manfredi 2013 41    In 1885, Pietro Vittanovich, the Padua superintendent of schools, and a teacher at the local secondary school illustrated the building in the Giornale dell'Ingegnere (journal and organ of the Collegio, the Milanese Association of Engineers) reproducing word-for-word, without quoting it, the very extensive steps of Boito's handwritten report (Vittanovich 1885). The article was then re-printed as an extract, with drawings corresponding to the constructed building. It cited numerous publications from the rest of Europe and the United States. Some of the books were available in Milan, kept in the library of the Politecnico, and the majority in Rome, at the Museum established by Bonghi, responsible for gathering documentation on school buildings.
The keen interest of architects and engineers is clearly visible both in the proliferation of local pamphlets, often difficult to obtain, and in the summary-a low-cost publication-by Giovanni Sacheri: the international scene is reconstructed, above all, by the materials exhibited or illustrated at the World Fairs of Vienna (1873) and Paris (1878) which explain "exotic" references, such as Norwegian schools (Sacheri 1883).

The Schools of via Galvani, Milan
The importance that Boito attributed to school architecture is confirmed by his design for the 24-classroom complex of the industrial district to the north of the city, a context very different to the historic centre of Padua, yet equally high-profile. 48 The Mayor, Gaetano Negri, awarded him the assignment on 7th April 1887, and the design was delivered on 6th November of the same year. On 13th December 1887, the City Council requested a reduction on the estimated cost of 610,000 lire. On 25th January 1888, Boito presented an alteration reducing the costs to 496,000 lire, which was approved by the City Council on 4th February. The central pavilion was re-sized: the first design planned a two-storey gymnasium together with a large drawing studio on the third floor, flanked on both sides by classrooms for manual work. Only the ground-floor gym remained. On final balance, the costs rose to 583,000 lire, that is 24,000 lire per classroom. The councillor who complained of costs tripling those of other schools designed by the Technical Office was, in any case, in error. Numerous opinions underlined-in agreement with the architect's report-the value of the building as a model and, indeed, the need to further raise the standard of school premises (Figs. 6 and 7). The classrooms, measuring 61.5 mq, were designed for 48 places. The surface area of the three windows, 1.4 m above the floor, totalling 15.3 mq, equalled a quarter of the floor plan. The wall on the corridor side was-unlike in Paduaopened up by windows corresponding to the external ones, and all of them were fitted with transoms for ventilation. Under the central windows, as many vents were created in the base of the external walls and the spine wall, measuring 1.2 Â 0.2 m, then openable and now blocked but easily recognisable due to their stone cornices, to improve ventilation. Bongioannini (Bongioannini 1870), followed by Ferrini, had already recommended air intake vents at the base of the walls and warm air outlets near to the ceilings, a mixing system closer to the French studies than to the English experiences, in which ventilation air was drawn in from below and out from above, thus using natural heating. However, extraction from below was, from a physical perspective, quite different from drawing in fresh air, as occurred in this case. In the lateral walls, channels were, in any case, provided in order to activate artificial ventilation, heating the air within the ducts using a gas burner to achieve an updraft.
However, heating, closely linked to ventilation, remained uncertain. Indeed, on 24th November 1887, the Health Commission recommended low-pressure steam heating, currently being installed at the premises of another school building, the Società di Incoraggiamento Arti e Mestieri. A long tradition was coming to an end, and technological progress was now rendering these more complex systems reliable.
The uncertainty of the report was pure opportunism, because the decision, partly due to cost limits, had already been made and the masonry ducts are clearly visible in the design drawings, attached to the ruling of 4th February 1888. However, only upon request by Boito himself, on 13th May 1889, did the procedure for selection and assignment by direct agreement begin. Five firms-Zanna, Guzzi & Ravizza, 48 All the documents concerning the school of via Galvani-if here are not different indicationsare located in in Archivio Civico del Comune di Milano (hereinafter ACMi), Beni Comunali, Finanze, cart. 226-227.

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A. Grimoldi and A. G. Landi Mussi, Lehmann, and Besana & Carloni-had submitted proposals, and a commission (consisting of architect Angelo Savoldi, Boito himself and, upon a Boito's proposal of his colleagues, Rinaldo Ferrini and Cesare Saldini) had limited the field to air ventilation and to three firms: Besana & Carloni, Guzzi&Ravizza, and Lehmann. The latter would be awarded the contract in accordance with a prefectural authorisation of 29th August.
8 The Companies' World?
The procedure followed makes it possible to reconstruct the state of the art in the sector, and-by comparison with conserved documents regarding other, similar installations -the ongoing developments. Renouncement of "maximum high-pressure" steam was due to its installation cost, correctly valued as double that of an air system, its burdensome maintenance and the need for specialist personnel to manage it. Air heaters, particularly in Milan where an early example dates back to the mid-eighteenth century (Forni 1997), was already traditional; indeed, advanced versions were also available which heated a lot of air to a relatively reduced temperature, while the "old-fashioned" models still offered little air at high temperature. These were not new issues but, rather, reflected the literature of ten or even twenty years before. Air heaters were merely large "circulation" stoves and also offered advantages in terms of scale. As the size of a building increases, it is advisable to centralise management in dedicated areas. Otherwise, it becomes necessary to transport fuel to higher floors, along corridors, at the expense of cleaning. With regard to their performance and actual savings, opinions differ, for example, between the young Bongioannini and Ferrini. Furthermore, much of the construction was in masonry, and the technology focused on the stove and on heating of the air rather than on its circulation. This was the focus of research in the '60 s, after the improvements introduced by Meissner in the 1820s (Forni 1997). Indeed, it would be tempting to say that research had ground to a halt: the manufacturers who introduced the most significant alterations, Zanna and Monti, were local, the latter continuing a firm established by Duke Antonio Litta in 1857. The former (Manfredi 2013 49 ;Manfredi 2017 50 ) probably relied on the Viennese experiences of the Vormärz and had established himself in Turin in 1852. The hot smoke of the inverted circulation stove was contained in two kinds of superimposed chambers made from metal sheet. Through these passed pipes channelling the outside air to which the heat was transmitted.
Duke hemispherical upper space for collection of the rising smoke, which then passed through a dense series of pipes and descended into a lower, equal-sized space beneath the stove. Each of these firms had headquarters in both Milan and Turin. In the first large, post-unification school building-that of corso di Porta Romana, at the corner of via Rugabella, Milan-the designer (the engineer Agostino Nazari) proposed "Litta system" heaters, 52 while, for the other large complex on via Santo Spirito-via Spiga-via Borgospesso, he repeatedly used Zanna ones, from 1870 to the 1880s. 53 Assignment was awarded through restricted invitations to tender. Alongside the best-known and most technically reliable firm, there was a world of "stove fitters" with shops and warehouses in the old centre of the city; small businesses that assembled pipes and cast-iron sheets or metal plates, perhaps supplied, in part, by larger companies. In other cases, such as Guzzi & Ravizza, a professional who designed the installation competed by probably coordinating workshops that performed the work. This was an initial step towards the birth of a true business. A summary overview of the most innovative companies was provided by Baseggio in the magazine L'Edilizia Moderna of 1892 (Baseggio 1892 54 ). These were predominantly concentrated between Milan and Turin, but their operating radius, after the unification, was nationwide, as demonstrated by the reference pamphlets printed several times by Litta-G. B. Monti, the Lehmann catalogues and the references included in the Besana & Carloni tenders. Edoardo Lehmann, 55 who was selected for the schools of via Galvani, proposed a patent filed in Geneva, by Louis Frédéric Staib (1812-1866), a solution also dating back to the 1850s and subsequently perfected (de Candolle 1867 56 ; Wartmann 1873 57 ). Bongioannini illustrated it and Ferrini described it using the name of Staib's successors, Weibel&Briquet (Weibel 2006). In a masonry parallelepiped, into which outside air flowed, the stove and smoke evacuation pipes were contained within a smaller, cast iron, concertina-type parallelepiped. This increased the ventilation surface area and transmitted the heat at a lower temperature to a larger quantity of air (Fig. 8).

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A. Grimoldi and A. G. Landi technical literature had already adopted a position, by them or by colleagues they cited with the due esteem. In proof of this, Boito entrusted the installations of his last great work, the Casa di Riposo per Musicisti (a retirement home for opera singers and musicians in Milan), to Lehmann. 58 Of Swiss origin, and a francophone despite his surname, as may be deduced from the rare and minor errors in his clear and correct Italian, Lehmann had established himself in Milan in 1879 as holder of a valued patent. In 1886, he completed his workshop, a block between the present via Lazzaretto, via Casati and viale Tunisia, at that time next to the railway tracks forecourt of the Central Station.
His project report reveals how the literature was transformed into high-quality practice, and how, during this practice, the resolution of certain problems developed. The building would have required six heaters, albeit of different powers, confirming the regulatory limit-15 m-for horizontal air paths. The ducts issued the hot air into the classrooms at 2.5 m above the floor and were constructed from hollow bricks which served as insulation. Additional hollow bricks doubled the solid brick wall of the boiler. Lehmann showed scepticism with regard to the ventilation shafts, which were too numerous-one per classroom-not to impair the function of the spine walls. The extraction activated by gas flame, when the boilers were switched off, would not, in practice, be used, and opening of the windows, which it was impossible to prevent, would, in any case, have undermined its function. As a last resort, it was more advisable to input forced air using a fan operated by gas motor which served to circulate the water, which, pending waterworks with adequate pressure, was, in fact, purchased. Mutatis mutandis, the famous alternative of the Hôpital Lariboisière was thus revived (Manfredi 2013 59  fragmented, confused and limiting set of instructions compared to the "best practices" of the period, and insufficiently applicable to the schools of smaller centres, the most numerous and necessary. Another frame of reference is provided by other Milanese schools. Between 1886 and 1889, the director of the via Galvani works, Angelo Savoldi, had built the schools of via Felice Casati, an initial attempt to propose more advanced school building standards. 60 Few documents have been conserved, and it is necessary to refer to the numerous publications, 61 testifying to their success and value as a model. The cost-approximately 454,000 lire-was just under 18,000 lire per classroom, 25% less than Boito's. The transparent surface had been reduced to a fifth of the area of a classroom, and the width of the corridors had been decreased to three metres. Climate control, both active and passive, was more complex: the windows were screened by high, narrow, four-part blinds which could slide in two different directions and back into the wall. The parapets consisted of two slender walls which enclosed a cavity. To the exterior, there was a series of terracotta rose windows. To the interior of these, there was a slit the length of the splay, enclosed by a metal frame with two sliding, perforated plates for blocking or opening the flow of air "like those of railway carriage ventilation doors". Four heaters-one for each wing of the building-were also present, manufactured by Guzzi & Ravizza. The hot air rose in the spine walls and was input into the classrooms at 1.8 m from the floor. In the skirting, on the other short side, were positioned the vents of the ventilation ducts, which rose up to the roof where they joined the chimney flues of the heater boilers, and the hottest smoke activated the outflow. In summer, at the point of the extraction chimney, the customary solution of the gas flame would have been adopted (Figs. 9 and 10).
The air heater, entrusted to Lehmann, appears in one singular case: the Realdo Colombo school in Cremona, whose designer, the city engineer Pietro Ghisotti, personally visited the schools of via Galvani and via Casati and consulted the documentation pertaining they (Landi 2017 62 ).
The via Galvani school was opened in autumn 1890, while the rapid population growth necessitated increasingly large spaces. During the second half of 1891, a City Council commission established the relative financial plan for three hundred classrooms over the decade at an average cost of 12,000 lire per classroom, half the amount Boito had calculated. This drastic reduction dictated a further simplification of the already minimal decorations. The changing rooms were renounced, the corridors were reduced to 3 m in width, the transparent surface decreased to a fifth or a sixth of the area of the classrooms, and the height of these dropped to 4.7 m; 60 The contract with the master builders Maggioni e Mazzai was underwritten on October 20, 1886 and the provisional trial was signed by the architect Giovanni Ceruti, on January 24, 1889 (ACMi, Beni Comunali, Finanze, cart. 223, fasc. 1). 61 Its most complete description perhaps in Mina (1892). 62 pp. 162-164.

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A. Grimoldi and A. G. Landi the 30 cm floor permitted a storey height of five metres, a ploy in order to comply with Regio Decreto no. 5808. As far as heating was concerned, the air heater was once again adopted.