458 



♦ KNOAVLEDGE ♦ 



[May 29, 1885. 



between the Swiss and Austrian railway systems, aa 

 advance of 10 ft. per day is made at one end by drills 

 similar to those employed at the St. Gothard, at the other 

 end 1.5 J, ft. per day with Brandt's hydraulic borer. 



In this country the Severn tunnel, 7,942 yards in length, 

 of which 2| miles are under the estuary, 96 ft. deep in one 

 part at high tide, is rapidly approaching completion. The 

 large quantity of underground water met with caused 

 unusual ditKculties and some temporary stoppages. The 

 Mersey tunnel, 3,820 yards in length, through red sand- 

 stone, of which 1,.300 yards are under the river, is now 

 completed. In the heading from the south side, a boring 

 machine, invented l^y Col. Beamont and Capt. Fisher, has 

 been employed. Tn this machine a bore-head 7 ft. in 

 diameter, fitted with discs or cutters of chilled cast-iron, is 

 rotated against the rock face by compressed air-engines. 

 The cutters can be turned round as they wear, thus bringing 

 a fresh edge to bear. The machine is advanced f in. each 

 revolution, and has bored 1.5 ft. in twenty-four hours. 



With reference to home railways, it is said that the 

 number of passengers carried, on the part of the metro- 

 politan line first ojiened amounted to 9,.500,000 in 1863, 

 during the past year it reached 114,.500,000. The running 

 of eighteen and nineteen trains per hour each way on the 

 busiest parts of these railways over the numerous junctions 

 and crossings, and that, too, with an almost complete 

 immunity from accidents, is pointed to as showing the 

 perfection to which railway working has now been brought. 



The growth of street tramways, from their first intro- 

 duction in their present form in 1867 to the present dav, 

 is briefly noticed, and considerable attention is bestowed 

 upon those masterpieces of human ingenuity and skill — 

 viz., bridges and viaducts, such as the International over 

 the Xiagara Eiver, 3,6-31 ft. in length, with a swing portion 

 of 364 ft, covering two spans of 160 ft., which can be 

 opened or shut in one minute by steam-power. Then there 

 is the Kentucky River Bridge, consisting of three spans of 

 37-5 ft., with a height of 27-5 ft. above low-water at the centre, 

 which was built out from the two sides of the ravine simul- 

 taneously with no other staging than a temporary timber pier 

 at the centre of each of the two land spans. The junctions 

 of the different members at the centre were effected one 

 at a time by slacking or keying up the lateral bracing, and 

 taking advantage of the range of temperature (30° Fah.) 

 between night and day. Among the other structures of 

 this class referred to are the Brooklyn Bridge, the Douro 

 "Viaduct, the Kinsua Viaduct, the Tay Bridge, and the Forth 

 Bridge. 



Interesting details are furnished concerning harbours 

 and the work involved in their construction, and a good 

 word is said on behalf of electricity as a source of illumi- 

 nation for lighthouses. 



The observations made upon the Suez Canal which was 

 opened for tratfic in Novembei-, 1869, are, at least for our 

 younger i-eaders, .sufficiently fresh to deserve quoting. It 

 is remarked that before the success of this great work was 

 assured, numerous insuperable difficulties were anticipated 

 by its optionents, but these have all been shown to be 

 without foundation ; thus it was stated by many persons 

 that the evaporation from the surface of the Bitter Lakes, 

 when water was admitted to them, would be so great that 

 many years would be required to fill them, and that a 

 strong current would always be maintained towards them, 

 and that they would become completely choked up by 

 a deposit of salt. But the entire space, containing 

 1,962,000,000 cubic yards, was tilled from the canal 

 between March 18 and October 24, 1869, and instead of a 

 new deposit of salt taking place the old banks of salt 

 were in six years dissolved away to the extent of 



88,000,000 tons. Analyses of the water of the lak^s 

 showed that the saltness of the water increased rapidly at 

 first as the banks were dissolved, but each year it has 

 diminished, showing that a constant interchange of water 

 between the lakes and the seas takes place. Observations 

 show that the north and north-west winds prevailing from 

 May to October raise the mean level of the sea at Port 

 Said and lower it at Suez, producing in September a 

 difference of level of one foot four inches, and causing a 

 current from the Mediterranean to the Red Sea. In the 

 winter the direction of the current is reversed by the pre- 

 vailing southerly winds. The importance of this work to 

 the commerce of the world is shown by the following table 

 of the traffic throuoh the canal : — 



1870. 

 1877. 

 1883. 



Komber of 

 Ships. 



.. 48G . 

 .. 1,G63 . 

 .. 3,307 . 



>'et Toimage. Receipts. 



. 436,609 £206,372 



, 2,355,447 1,310,973 



. 5,775,861 2,740,933 



It is said, in connection with the construction of the 

 metropolitan intercepting and outfall sewers, in all 82 

 miles in length, that these works involved the use of 

 318,000,000 bricks, 880,000 cubic yards of concrete, 

 3, -500,000 yards of excavation, and the erection of pumping 

 stations of 2,380 horse-power collectively, the total cost of 

 the whole being £4,100,000. 



With reference to the exhibits themselves, it is greatly 

 to be regretted that they do not include models of at least 

 a few of the magnificent monuments of human energy 

 which have been reared within the past quarter of a cen- 

 tury. Specimens, mechanical appliances, and a few models 

 make up a collection which is far short of what in the year 

 1885 it ought to be. 



The pet scheme of Sir E. Watkin, who is apparently 

 ambitious to secure a position akin to that of M. de Lesseps, 

 is exhibited in a prominent position by the Submarine 

 Contineotal Railway Company. The proposed Channel 

 Tunnel is illustrated by a series of models and maps. The 

 first stand carries a model of the bed of the sea in the 

 Straits of Dover, showing the course of the proposed sub- 

 marine tunnel and the geological formation along its centre 

 line. The second stand bears a model of the bed of the 

 sea in the Straits of Dover, showing the submarine chalk 

 formation at right angles to the centre line of tunnel i 

 while the third has a model of a boring machine con- 

 structed by Messrs. Beaumont it Co. for the experimental 

 works of the Submarine Continental Railway Company. 

 There are three cartoons purporting to be: — (1) Map of 

 the geological formation in the Straits of Dover, showing 

 the course of the proposed submarine tunnel. (2) Longi- 

 tudinal section of the j)roposed submarine tunnel, showing 

 the bed of the sea and the geological formation along the 

 centre line. (3) Cross sections of the geological formation 

 taken at right angles to the centre line of tunnel. 



Xear the centre of the court is exhibited a few models 

 of Roper's suggested appliances for blocking the proposed 

 tunnel. Oue of these devices is to fill a portion of the 

 tunnel with earth, stone, and rock by dropping the mate- 

 rial from a reservoir above the tunnel. It could scarcely 

 be urged, however, that such an obstacle could be very 

 serious to men determined to get through. 



An exhibit which is likely to attract some attention on 

 the part of Londoners is that of Baines ifc Heath's water 

 meters, which are claimed to be sufficiently accurate to 

 measure to the dripping of a tap. 



The very extensive and successful adoption of zinc for 

 temporary buildings, ic, has recently borne fruit in the 

 projjagation of a number of plans for using the metal. The 

 show made by Messrs. Braby it Co. is a good one, and is 



