860 REPOKT— 1892. 



unusual in the dimensions or the treatment, from an engineer's point of view. The 

 roofs are neither very great in span nor original in design, the main object liaving 

 ■wisely been to cover a vast area in the cheapest and the most expeditious manner 

 consistent with a realisation of the best effects for the special purpose for which 

 each building was intended. Considerable interest, however, attaches itself to the 

 foundations of all the main buildings. In constructing these, the system found 

 most useful for the great permanent buildings of the city of Chicago has been 

 adopted for these temporary structures ; that is to say, a system of independent 

 platform foundations, each unit of which distributes, independently of all the 

 others, a safe proportion of the load which has to be supported by the thin bed. 

 This is a peculiarity which the local conditions of the ground render advisable. 



The exception above referred to when spealdng of the engineering features of 

 the exhibition buildings is found in the great hall devoted to Manufactures and the 

 Liberal Arts : this will have the largest roof that has ever yet been constructed. The 

 building covers an area of over thirty acres, and consists of a centrid galleiy, 387 

 feet clear span and no less than 210 feet in height : the length of this vast hall is 

 1,237 feet and the great roof is hipped at each end. It is surrounded with a series of 

 galleries, insignificant by contrast, both as regards height and span. The trusses 

 forming the great roof are of steel, and resemble to some extent, especially as re- 

 gards size, the somewhat smaller and considerably lower arches of the machinery 

 hall of the Paris Exhibition, which up to the present has surpassed any other 

 structure of the kind. 



It will be remembered with what interest engineers of every nation watched 

 the erection of that great roof, which was undoubtedly a triumph of the contractor's 

 skill. The erection of the Liberal Arts building is a work of much greater magni- 

 tude, but it is being carried out bj' simpler means and with greater facility than 

 tlie Paris machinerj- hall. 



A travelling stage, wide enough to include two trusses and the whole width of 

 the building, is employed. On this staging are two towers, framed in timber, higher 

 than the roof. The erection of the trusses is carried on from the ground and from 

 the staging to a height of about 100 feet, that is to say, to the level of the main plat- 

 form of the stage. The upper halves of each pair of trusses are put together 

 upon this platform, and when the lower portions are completed and connected by the 

 longitudinal bracing, the inner members of the upper and lower sections are con- 

 nected by means of pins, so as to form lunged joints. By means of powerful hoist- 

 ing apparatus, worked from the floor of the stage, the upper halves are then hoisted 

 to their final position, turning on the hinges. When fully raised the central 

 joint is made good, the outer members of the upper and lower halves are rigidly 

 connected, the hinges are removed, and the permanent joints are completed by 

 riveting. In this way the work is rapidly carried on, and it is expected that the 

 building will be ready for the great inaugural celebration in October next. 



2. The Application of Desfructom, eapecialhj to the Electric Lighting of 

 Edinburgh. Dij Professor G. Forbes, F.B.S., F.E.S.E. 



3. The Disposal of Befiise} Bij G. Watsox. 



1. Introbuction. — The Present Position of the Queslion. — The waste products 

 chiefly dealt with are those at present coming under the administration of local 

 authorities, comprising ashbin refuse, and market garbage, fish, and other offal, 

 street sweepings, excremental matter, and manufacturers' refuse, the latter being a 

 term substituted for 'trade refuse' in order to discriminate between shop and 

 market refuse and the waste products of manufacture. 



The methods of disposal now generally adopted are, in most instances, in- 

 complete, wasteful, and injurious to the public health. They may be briefly 

 classified as follows : — 



' Published in crtciiso in Eiiffiiicerin/f for Sept. 16 and 30, 1892. 



