he made as the president of the Superior Commission, June 15, 1888, "is to instruct the public in the history of the processes of manual and mechanical labor, which in the passage of centuries have resulted in the modern industrial utensils used in the arts and trades." This exhibit has a particularly historical and technical character. It is far from excluding objects of art, for in several ages the utensils, those especially which were used in the liberal arts, were veritable jewels, either from their elegance of form, or from the richness of their material, or the grace of their details. We find chefs-d'oeuvre, for instance on a geographical map, on the handle of a chisel, on the barrel of a musket. Our ancestors were not possessed with the same passion for speed and cheapness that possesses us. Industry lost, perhaps, but the arts were the gainers. The aim of the retrospective exhibition is well defined. It is to retrace with broad strokes by means of the reproductions of diagrams and authentic monuments the stages of human genius. To achieve this result it was necessary to associate with the retrospective exhibition of labor that of anthropologic science, in order to show in the outset what man was when he left the hands of nature in the different physical forms of different races. The exhibit of anthropological science and history of labor comprises then five grand divisions—first, anthropologic and ethnographic science; second, the liberal arts; third, arts and trades; fourth, means of transportation; fifth, military arts.

The central nave of the Palace of the Liberal Arts is wholly occupied by this exhibit. Grand porticos and galleries of woodwork with platforms in the lower story, form four grand divisions with interior courts that approach by monumental staircases opening under the dome upon each side of the rotunda, which occupies the centre and shelters the theatrical exhibit. All around the porticos and galleries full panels were reserved upon which M. Charles Touché placed decorative compositions broadly treated in aquarelle illustrating, so to say, the history of labor.

AN INGENIOUS PLAN FOR STRAIGHTENING WALLS.—Yankees, as a rule, are equal to any emergency; what the average Yankee mechanic fails to conjure up at a time when his wits are most needed, leaves very little room for foreign genius to think and work in. Yet it remained for M. Molard, a French architect, to contrive an original and ingenious plan for straightening the walls of the Conservatoire des Arts et Métiers, which threatened an absolute collapse owing to the extreme weight of the roof. A series of strong iron bars were carried across the building from wall to wall, passing through holes in the walls, and were secured by nuts on the outside. In this state they would have been sufficient to have prevented the further separation of the walls by the weight of the roof, but it was desirable to restore the walls to their original state by drawing them together. This was effected in the following manner: Alternate bars were heated by lamps fixed beneath them. They expanded, and consequently the nuts, which were previously in contact with the walls, were no longer so. The nuts were then screwed up so as to be again in close contact with the walls. The lamps were withdrawn and the bars allowed to cool. In cooling they gradually contracted and resumed their former dimensions; consequently the nuts, pressing against the walls, drew them together through a space equal to that through which they had been screwed up. Meanwhile the intermediate bars were heated and expanded, and the nuts screwed up as before. The lamps being again withdrawn, they contracted in cooling, and the walls were further drawn together. This process was continually repeated, until at length the walls were restored to their perpendicular position. The gallery may still be seen with the bars extending across it, and binding together its walls.—Philadelphia Record and Guide.

LOSS OF POWER BY RADIATION OF HEAT.[3]