APPRÉCIATIONS, XIX

Quant aux autres corps, il est vrai que plus on muitipliera les sections, suivant le besoin, plus l'approximation sera proche de la vérité,

Cette formule est véritablement eurieuse par sa généralité

mm vs... nm mm mm mm mm mm mm mm mm

J'approuve et récotnimane la méthode de Mr, Baillairgé telle que proposée par lui.

Extrait d'une lettre Aug. Humbert à V, Vannier, Paris le 4 Aout 1872.

J'ai fait recevoir Ar, Baillairgé Membre Titulaire de la Société de Vulgarisation pour l'Enseignemet du Peuple,

A défaut de son tableau que nous n'avons pas, j'ai exposé su photographie à Paris et à Lyon.

Son tableau appelle tous les regards à l'exposition, on nr'interroge, on me demande des explications que je donne de mon mieux, et cela intéresse beaucoup. J'ai done tout lieu de compter sur un SUCCÈS,

Je considère qu'un tableau stéréométrique celui dont vous w’envoyez le prospectus est le complément indispensable de la règle pour la plupart des personnes qui peuvent avoir besoin de s’en servir et dans les colléges, ete., ce tableau sera en outre d'un grand secours aux élèves qui écrdient la géometrie analytique à trois dimensions et la trigonométrie sphérique.

Westmeretond Point N. B. 4. Nov. 1871. Ÿ: STECKEL,

From the Saturday Budget of May 6, 1871.

Tue Quesec Sonooz or AkRrs AND TRrapes.—On Thursday evening last, was closed for the season the Quebec School of Arts and Trades inaugurated on the 23rd of January last under the auspices of the Montreal Board of Arts and Manufactures,

Thus the first course of lessons has lasted little over three months, during which short time Mr. Baillairgé who kindly acted as professor for the season has managed to initiate two classes of pupils, the one speaking the English, the other the French language into all the mysteries and intricacies of description Geometry and Mensuration of Surfaces and Solids.

The extraordinary progress made by the oupils, in the short space of three months, in stereometry or the mensuration of solids, is attributable to the grand and important tiscovery by their professor, Mr. Baïillairgé, of a rule, one and the same applicable to every known form, from a pyramid co a sphere, from a stick of timber to a vessel or other body of any shape or dimensions.

D &.4 LE TABLEAU STÉRÉOMÉTRIQUE.

The pupils have been taught to combine the elementary geome trical forms into designs for paperings, carpetings, oil-cloths, tile and marbie floorings, ornamental glazier’s work, fretwork, tracery, &e. They have learned to measure the superficial contents of any figure from a square or triangle to a cirele, ellipse, lune or zone, We have seen them in a very few minutes by the help of Mr. Baillairgé’s new and beautifuly simple and aceurate rule arrive at the number of gallons in à cask of any size or shape. We have seen them determine by the same rule the exact weight of à shell, the true contents and weight of a hollow cast-iron column, the size and weight of à pontoon and its draught of water. They have been taught to calculate the exact eubical contents and weight of irregular forms, such as statues and other carvings whether exeeuted in stone or iron, &e., in fact à complete course of geometry, mensuration, weights, measures, and specific gravities, &e., and in addition to all this the horse-power of any stream or fall of water, and of any steam engine.

Baillairgé’s stereometrical tableau.—Our engraving is a perspective view of the above named educational device, which has been patented for its inventor, Mr. Baillairgé, of Quebec, in the United States, Canada and Europe. It consists of à board, about five feet long and three feet wide, with some two hundred wooden models, comprising, so to say, all the elementary forms, their segments, and sections, and numerous other solids, simple and compound,

The tableau is set in an appropriate frame with glass covering, so as to exhibit the models while exeluding the dust. The front can be opened at pleasure so as to afford access to the models, each of which is merely supported on the board by à round nail or wire, which admits of its easy removal and replacement by teacher or pupii. The instruction conveyed by this tableau, anpealing, as it does, to the uneducated eyeand mind, is, theinventor thinks, destined to be of great use in developing the intelligence of the untaught masses of mankind. He expects to introduce it iuto all the educatiopal institutions ofthe United States and elsewaere, as it is now being disseminated in Canada ; and he has no doubt that the tableau will also find its place in the studio of the engineer and architect to whom the models will be sugestive of various forms and relative proportions which cannot fail to aid them in their pursuits. The rapid success attained by à school in Quebec, in mensuration of all kinds of surfaces and yet higher mathematics, including conie sections, was attributed to the use of this tableau. Every tableau is inscribed with a rule for finding the solid contents of any body, called “the prismoidal formula.” This formula has been shown, by Mr. Baillairgé in his treatise on geometry aud mensuration published in 1866, to be