March 5, 1885] 



NA TURE 



421 



the same initial strain. So far as novelty in girder-construction 

 was concerned, the suspended cantilever of the Forth Bridge, 

 now in course of construction, afforded the most notable instance. 

 It was difficult to see how a rigid bridge, with 1700 feet spans, 

 and with the necessity for so much clear headway below, could 

 have been devised without the application of this principle. A 

 noteworthy example of the use of pneumatic appliances in 

 cylinder-sinking for foundations was also in progress at the 

 Forth Bridge. At the New Tay Viaduct, the cylinders were 

 being sunk while being guided through wrought-iron pontoons, 

 which were Boated to their berths and were then secured at the 

 desired spot by the profusion, hydraulically, of four legs, which 

 bore upon the bottom, and they, until they were withdrawn, 

 converted the pontoon from a floating into a fixed structure. 



The President next traced the contest between canals and 

 as modes of internal transit, in contrast with 

 railways, and referred to the improved rate of transport on 

 canal- by the substitution of steam- for horse-haulage, and by a 

 diminution in the number of lockages. He also alluded to the 

 hydraulic canal lift on the River Weaver, and to a similar 

 application in the Canal de Neufosse, in France, for overcoming 

 a great difference of level, and reducing the consumption of 

 water and' the expenditure of time to a minimum. The great 

 feature, however, of late years in canal engineering, was not 

 the preservation, or improvement, of the ordinary internal canal, 

 but the provision of canals such as the completed Suez Canal, 

 the Panama Canal in course of construction, the contemplated 

 Isthmus of Corinth canal — all fur saving circuitous journeys in 

 passing from one sea to another — or in the case of the Manchester 

 Ship Canal, for taking ocean steamers many miles inland. The 

 rivalry between canal-engineers and railway-engineers was illus- 

 trated by the proposal to connect the Atlantic and Pacific oceans 

 by means of a ship-railway, the details of which scheme were 

 before the public. 



In harbour-construction, the principle adopted in the Liffey at 

 Dublin w : as referred to, where cement-masonry was moulded 

 into the form of the wall, for its whole height and thickness, 

 and for such a length forw aid as could be admitted, having 

 regard to the practical limit of the weight of the block. The 

 block was then carried to its place, was lowered on to the 

 bottom, which had been prepared to receive it, and was secured 

 to the wall by groove and tongue. The apparatus by which the 

 blocks, weighing 350 tons each, were raised, and transported to 

 their destination, was then described. 



Consideration of sub-aqueous works necessarily led to appliances 

 for diving ; and here the President said a few words about the 

 " bateau-plongeur " used on the "barrage " of the Nile. Beyond 

 improvement in detail and the application of the telephone, there 

 was probably no noveity to record in the ordinary dress of the 

 diver. But one great step had been made in the diver's art by 

 the introduction of the chemical system of respiration. A 

 perfectly portable apparatus had been devised, embracing a 

 chemical filter by which the exhaled breath of the diver was 

 deprived of its carbonic acid. The diver also carried a supply 

 of compressed oxygen to be added to the remaining nitrogen, 

 in substitution for that which had been burnt up in the process 

 cf re. piiation. Armed with this apparatus, a diver during one 

 f.f the inundations which occurred in the construction of the 

 Severn tunnel, descended into the heading, proceeded along it 

 for some 330 yards (the depth of the water above him being 

 in I closed a sluice-door through which the water was 

 entering the excavations, and thus enabled the pumps to unwater 

 the tunnel. Altogether, this man was under water for one hour 

 and twenty-five minutes without any communication with those 



There were, happily, cases of sub-aqueous tunnelling where 

 the water could be dealt with by ordinary pumping power, and 

 id was capable of being cut by a tunnelling 

 machine. In the Mersey Tunnel, in the New Red sandstone, a 

 heading 7 feet 4 inches in diameter, a speed of 10 yards in 24 

 hours had been averaged, while a maximum of over 14 yards 

 had Leen attained. In the experimental Channel Tunnel in a 

 7-feet heading in the gray chalk, a maximum speed of 24 yards 

 bad 1« en arrived at in the 24 hours on the English side, and on 

 tlie French side of 27^ yards in the same time. In ordinary 

 land-tunnelling, since 1862, there had been great progress, by 

 the substitution of dynamite, and preparations of a similar 

 nature, for gunpowder, and by improvements in the rock-drills 

 worked by compressed air, used in making the holes into which 

 the explosive was charged. In boring for water, and for many 



other purposes, the diamond drill had proved of great service. 

 Closely connected with tunnelling-machines were the machines 

 for "getting" coal, which, worked by compressed air, reduced 

 to a minimum the waste of coal, relieved the workman of a most 

 fatiguing labour in a constrained position, and saved him from 

 the danger to which he was exposed in the hand operation. The 

 commercial failure of these machines was due to trade opposition, 

 and it was to be feared that like prejudices would prevent the 

 introduction of the lime-cartridge in lieu of gunpowder. 



With regard to the great source of motive power — the steam- 

 engine — it was difficult to point to any substantive novelty since 

 1862. But the machine had been more and more scientifically 

 investigated, and the results had been practically applied with 

 corresponding advantages. The increase in initial pressure, the 

 greater range of expansion, the steam-jacketing of the vessels in 

 which the expansion took place, had all led to economy. 

 Double-cylinder non-condensing engines were now currently 

 produced, which worked w ith a consumption of only 2% lbs. of 

 coal per I. H. P., or 27 lbs. per H.P. delivered off the crank 

 shaft, equal to S2 millions of duty on the Cornish-engine mode 

 of computation. When these results were augmented by the 

 employment of surface-condensation, an I. H.P. had been ob- 

 tained for as low as ii lbs. of coal, and it was commonly 

 obtained, in daily work, for from 2 lbs. to 2\ lbs. But in the 

 use of steam as a heat-motor, the largest portion of the heat 

 passed away unutilised. This defect had been sought to be 

 overcome by a regenerative steam-engine, but it was not success- 

 ful. Heated-air engines had hitherto only been found applicable 

 where small power was required. Another form of heat-motor 

 — the gas-engine— was daily coming into general use up to 30 

 I.H.P.. By a change in the mode of burning the mixture, and 

 of utilising the heat thereby generated, the injurious shock of the 

 early forms of gas-engine, and their large consumption of gas, 

 were obviated. Comparing a gas-engine with a non-condensing 

 steam-engine consuming 5 lbs. of coal per I. H.P. per hour, and 

 demanding therefore, at one shilling pe% cwt., only one half- 

 penny for the purchase of coal, the extra cost for working the 

 gas-engine was well repaid by the saving of boiler-space, of the 

 wear and tear of the renewal of the boiler, of the consumption 

 of coal while getting up steam and during meal-times, of the 

 saving of wages, of the freedom from boiler explosions, and of 

 the cessation of smoke production. A motor had been recently 

 tried where no fuel w r as employed directly, but where a boiler, 

 being filled with water and steam under pressure, had its heat 

 maintained by exposing caustic soda, contained in a vessel sur- 

 rounding the boiler, to the action of the waste steam from the 

 engine, the result being that, as the moisture combined with the 

 caustic soda, sufficient heat was developed to generate steam and 

 keep the engine working for some time. Trials had been made 

 with this motor for propelling a launch and for working a 

 tramcar. 



With respect to other motors, viz. those driven by wind or by 

 water, in France an improvement had been made in water- 

 wheels by which it was asserted that 85 per cent, of all the 

 energy residing in a low fall of water had been converted into 

 power. In turbines al.- o there had been considerable develop- 

 ment during the last twenty-two years, and they were very 

 efficient where a high fall of water had to be utilised, or where, 

 in the case of a low fall, great difference in the working head, 

 and in the level of the tail-water, had to be provided for. 



Next to the subject of motors came the transmission of power. 

 In its restricted sense, the transmission from one part of a 

 machine to another, reference might be made to the increasing 

 use of multiple-rope driving-gear in lieu of belts, to inclined 

 spur-gear for diminishing noise, and to that kind of frictional 

 gearing to which the name of " nest-gearing " had been given. 

 Where, however, the transmission was to long distances, means 

 were being adopted for supplying power — i.e. water under pres- 

 sure or compressed air— through mains laid down in the streets, 

 in a manner similar to that in which gas and water were now 

 supplied for domestic use ; and in New York and other cities of 

 the United States high-pressure steam was similarly conveyed 

 and delivered to the consumers, both for power and for heating. 



Sir Frederick Bramwell also remarked upon the continuous 

 rolling of bars of steel for tyres, upon the right way of making 

 boiler-shells and boiler-flues, upon tidal motors, upon "dirigible" 

 balloons, upon the Maxim machine-gun, and upon the applica- 

 tion of submarine mines and torpedoes for the defence of sea- 

 ports. In regard to waterworks, he could not adduce any mate- 

 rial improvements in those dependent upon storage, or in 



