s'CH r:\nii5rnoN. 



'.itcctiirc i.r different, enuntries 



or booses for tin- Industrial 



. as link- deserving of especial 



I in- imitation. 



iistinu'tiishing feature of tin- Kxhibition- 



liuilii; ''-HI of ventilation, \vliii-li 



1-1 u- u>e of jets of compressed air tor 



!i- in by iiiilurtion tlif requisite supply of 



nil- to tin.* variou- tlo partments oft la- bnild- 



\rouinltlio whole of the exterior of the Ex- 

 hibition-building is carried ft large subterranean 

 gallery, dr. rows of pillars into three, 



eaeh aboal '. ft. 10 in. in width. A wall com- 

 pletely divides the two inner galleries from tlie 

 HINT <me; tlie inner serve as cellars for the 

 various restaurants, the outer for ventilating 

 purposes. This outer annular gallery commu- 

 es with tlio external air by means of 16 

 L-hafts, ea -h 1) ft. 10 in. in diameter, disposed 

 symmetrically around the building, and having 

 their openings distant about 66" ft. from the 



I covered way. 



In order to conduct the nirfrom the annular 

 gallery to the interior of the palace, 16 radial 



rrancan shafts were constructed, each ex- 

 tending under tlie palace for a length of 394 

 from the annular subterranean gallery 



. to the centre. 



l'nder each of *the three main annular ave- 

 nues of communication between the machinery 

 gallery and the- central court, ventilating con- 

 duits were constructed, communicating with 

 the. Ki radial shafts, the shafts under the an- 

 nular avenues being formed in sections extend- 

 ing from one radial shaft to the next, each 



ii lieing in communication with one ra- 

 dial >haft only. Each section of the building 

 can thus have' its supply of air regulated inde- 

 pendently of that of the others. The air is 

 admitted into the building from the circular 

 branch shafts. This induction of the external 

 air is effected by placing in each radial subter- 

 in gallery, almost under the external wall 

 of the building, a jet or nozzle supplied with 

 compressed air, this air as it escapes acting like 

 the steam i-.-uing from a blast-pipe, and carry- 

 ing in along the radial gallery a quantity of 

 air with it by induction. The 16 jets are 

 formed by their connecting pipes into four 

 groups, and these groups are supplied with 

 compressed air by the four set-; of air-compress- 

 ing machinery. The diameters of the pipes 

 1 ;iding from the nir-compressing machinery 

 to the jets vary from 1 ft. to 2 ft. Each jet- 

 pipe has a flat end, having formed in it four 

 sector-shaped openings disposed symmetrically 

 around the centre. The- openings when com- 

 pletely uncovered have a united area of 2,015 

 sq. in.; but this area can be reduced by means 

 of a valve. 



The engines for furnishing the necessary 

 supply of compressed air are four in number, 

 and they have a total power of 105 horses 

 nominal. The air is supplied to the jets at a 



uro of from 29^ to rnj in. of water. 

 T!K- escapo of the vitiated air is allowed to 



!aco through Venetian* in the roof. Tin- 

 COSt of ventilating tlie building ha-. 

 by M. Piurron i! SI ir, in 11 paper r ad l.v 



him before the Soci6t6 des Ing6nieurs ' 

 of France, to bo about 0.1 franc per 858,165 

 cubic feet of air supplied. 



CIVIL K- \M) IViiuo WORKS. In 



the French section only is there a satisfactory 

 exhibition in civil engineering proper; the 

 other European nations, as well as the Uni- 

 ted States of America, are but slightly repre- 

 sented. 



The French collection is unrivalled. It con- 

 tains models, admirably got up, of bridges, vi- 

 aducts, reservoirs, docks, tunnels, etc., with 

 complete plans illustrative of all recent public 

 works; a brief but clear report of each work 

 is to be found in a volume published under the 

 auspices of the Ministero d'Agriculture, du 

 Commerce, et des Travaux Publics. 



The most important exhibit in the English 

 section is the application to light-houses of the 

 dioptric system of light of Augustin Fresnel. 

 The dioptric system has been recently admira- 

 bly described by Mr. Chance in a paper read 

 at the Institution of Civil Engineers. 



The machine for the production of the light 

 consists essentially of six brass wheels, with six- 

 teen bobbins of insulated copper attached at 

 equal distances to the circumferences of each 

 wheel ; inside each bobbin is a hollow core of 

 soft iron ; the wheels are all fixed upon a shaft, 

 which is driven by a steam-engine. In turn- 

 ing, every core of each wheel is brought at the 

 same instant between the opposite poles of two 

 magnets, which pair of poles it also quits at 

 the same instant. The core of every bobbin 

 has its magnetism thus reversed by the revolu- 

 tion of the wheels 107 times per second. This 

 reversing of the magnetism induces a current 

 of electricity in the bobbins ; the combination 

 of the currents produces one of sufficient inten- 

 sity to give a powerful light. 



Prussia exhibits a system of centring lately 

 used in tunnelling, the essential feature of which 

 is the substitution of a portable iron framework 

 for the ordinary timber centring. This system 

 has been adopted in the construction of the 

 tunnels of Narusen and Ippensen. 



In the Southern States of Germany a remark- 

 able example of cheap railway-bridge construc- 

 tion is exhibited in the Bavarian section, by a 

 model, on a scale of ^Vth full size of a bridge 

 of boats over the Rhine, between Maximiliansm 

 and Maxau. The bridge consists of twelve 

 rafts, six of which are easily removable to 

 allow the passage of boats; these rafts are 

 carried by thirty-four pontoons, or boats, sub- 

 stantially built of oak, of which material are 

 also the principal beams and the upper planking 

 of the roadway. ' These pontoons are 65 feet 6 

 inches long, 12 feet 2 inches broad, and 4 fe<. t 7 

 inches deep; except the two pair next the 

 shore, which are .-ornewhat longer. 



in the Italian section is an atlas containing 

 plans and sections of the great tunnel of v 



