Feb. 9, 1888] 



NA TURE 



355 



and hydrogen evolved exactly proportional to the current 

 passing. If a silver voltameter were included in the circuit, for 

 every milligramme-equivalent (108 milligramme!-) of silver de- 

 jwsited, I milligramme-equivalent of hydrogen occupying li*2 

 cubic centimetres and 8 milligrammes of oxygen occupying 5 •6 

 cubic centimetres at 0° C. and 760 millimetres, were liberated. 



Although Sir William Thomson did not publish"any electrical 

 theoretical work in 1887, he perfected during that year his 

 practical electrical measuring instruments. They are in use at 

 the Grosvenor Gallery central station in London. There are 

 no more beautiful or accurate instruments in the world, and they 

 reach over an enormous range both of potential and of current 

 measurement. They were admirably illustrated and described 

 in Industries of January 27 by Prof. Fleming. 



Hertz {^Wiedemann Ann. 1887), has shown that the ultra- 

 violet rays have an influence on the passage of sparks. E. 

 Wiedeman and H. Ebert have been repeating and verifying his 

 experiments. The effect of light falling on the spark region was 

 to lower the potential required to produce it. If a succession of 

 sparks be sent, and a telephone be used, the effect of light 

 falling on the sparks was to change not only the note but the 

 whole character of the sound heard in the telephone. If a 

 Geissler's tube were used, an intermittent and irregular dis- 

 charge became steady and continuous. The effect was evident 

 only on the negative pole. 



It is known that the magnetic qualities of iron diminish con- 

 siderably when raised to 525° C. (red heat), but iron remains 

 magnetic up to 650° C. Nickel loses its magnetic properties 

 suddenly at 300° C. Lodeboer recently (January 9) read a 

 paper before the Academie des Sciences, in which he showed 

 that with magnetizing forces of 35, loo, and 200 C.G.S. units 

 the iron retains its magnetic properties up to 6So° C. ; that 

 beyond this temperature it rapidly loses them ; that at 750° C. 

 they scarcely exist, and at 770° C. they entirely disappear, to re- 

 appear only on cooling. It is known that the specific heat of 

 iron undergoes a change of condition between 660^ and 720° C., 

 and the coincidence of these two changes is very interesting. 



The treatment of sewage by electricity is, it seems, likely to 

 receive a practical test at the Metropolitan Board of Works' 

 outfall at Crossness. Mr. Fewson, of Buckingham, made some 

 experiments in this direction at Wimbledon last summer, and 

 now Mr. W. Webster is about to do the same thing at one of 

 the large tanks on the Thames. The electric current is said to 

 have a wonderful disinfecting and purifying influence. The 

 evolution of gas stirs up the liquid, the nascent oxygen is brought 

 into rapid contact with the impurities and reduces them, precipita- 

 tion is expedited, and the whole cleansed. It is to be hoped 

 that the cost will not swamp this new and useful field for 

 electricity. 



The extraordinary rise in the price of copper has attracted 

 much attention to the use of iron for lightning conductors. 

 Prof. Silvanus Thompson advocates iron in preference to copper 

 under all circumstances. Iron is much used by the War Depart- 

 ment to protect magazines. Dr. L. Weber recommends it even 

 in a solid form rather than as a stranded rope, but the latter form 

 is much more portable and workable ; moreover, Prof. Hughes 

 showed it to be less subject to self-induction than a solid rod — 

 an obstruction not to be neglected. Iron conductors are stronger, 

 much cheaper, less easily fused, and less liable to theft than 

 copper. There can be no objection to the use of iron. 



The electro-deposition of aluminium has attracted much 

 attention since the introduction of the Cowles process. 

 Herman Reinbold has proposed the following solution, with 

 which he has obtained good but small results : alum 50 parts, 

 water 300 parts, aluminium chloride 10 parts. This solution is 

 heated to 200° F., and after cooling 39 parts of potassic chloride 

 are added. 



THE INSTITUTION OF MECHANICAL 

 ENGINEERS. 



"T^HIS Society held its forty-first annual general meeting in 

 *■ the theatre of the Institution of Civil Engineers on 

 Thursday and Friday of last week. After the Annual Report 

 had been presented and accepted, Mr. John Richards' paper 

 " On Irrigating Machinery on the Pacific Coast " was read and 

 discussed. The need of irrigation in this district arises from 



three causes : the lack of rain, which ceases altogether along 

 the coast in summer-time ; the want of surface-water ; and the 

 free percolation into the sandy soil beneath. The whole of the 

 land in the country, excepting the low-lying sedimentary plains 

 near the mouths of the rivers, and around the Bay of San 

 Francisco, where water reaches the surface by capillary satura- 

 tion, requires irrigation. Nearly all the land upon which water 

 can be led, either by training small mountain streams, or by 

 leading long canals from the rivers, has been occupied, so that 

 the only remaining resource for getting water will be by lifting 

 it from the rivers or the gravel strata by machinery. The paper 

 is descriptive of the various pumps and hydraulic rams employed, 

 and was illustrated by means of thirty- five figures. 



Mr. William Geipel's paper " On the Position and Prospects 

 of Electricity as applied to Engineering " refers to those branches 

 of electric engineering which involve the employment of con- 

 siderable power, and are in some way or other connected with 

 the use of dynamos. They comprise electric transmission and 

 distribution of power, and electric lighting, locomotion, and 

 metallurgy. 



In the author's opinion the transmission and distribution of 

 power by electricity will occupy in the near future most of the 

 attention of the electric engineer. Owing to its simplicity, the 

 ease with which an electric motor can be applied to any purpose 

 requiring power, and its high efficiency, it is certainly an 

 approach to an ideally perfect sy^■tem of transmission. In the 

 United States great strides have been made in the applications 

 of electric motors, which already rival those for lighting purposes. 

 One of the great advantages of these applications is due to the 

 low efficiency of belts and shafting where high speed is required 

 and the demand for power is variable. By getting rid of shaft- 

 ing the necessity for additional stability in buildings is obviated, 

 and constant lubrication is done away with. The distribution 

 of power by elec'ricity from a central station to small users can 

 be effected from the same mains and generators as are used for 

 electric light purposes ; as to whether gas through the medium 

 of gas engines or electricity by means of electric motors should 

 be used, will become entirely a question of economy and con- 

 venience. On the one hand the electric motor can be started 

 and stopped with the greatest ease, it requires little attention, 

 occupies little space, and can be placed anywhere, while against 

 the use of the gas engine, the author brings forward its irregu- 

 larity of speed owing to the intermittent impulse and the wear 

 and tear in the valves and working parts. Shunt motors, which 

 are now almost exclusively used, possess a practically perfect 

 power of self-control, not only over their rate of speed with 

 varying load, but over the energy absorbed, for they help them- 

 selves, as it were, to only such an amount of energy as will 

 enable them to deal with the work imposed upon them. Another 

 advantage in shunt motors, first pointed out by the late Sir 

 William Siemens in 1880, is that they act as generators when 

 themselves driven by any extraneous power, without any com- 

 plication of the switch gear required with series motors. The 

 author refers to various installations which have already taken 

 place in Europe and America, which are paying their way, 

 whilst at the Falls of Niagara plant is being put down to dis- 

 tribute power obtained from the Falls to neighbouring towns, 

 including Buffalo, which is twenty miles distant ; the amount of 

 power is stated at 15,000 h.p., of which 10,000 h. p. is contracted 

 for at ;^3 per h.p. 



Electricity has been applied with efficiency in collieries for 

 underground hauling, pumping, ventilating, and drilling ; in 

 ship-yards and similar works it has been proved to be a suitable 

 and economical means of transmitting power for riveting, drill- 

 ing, &c. 



In its application to the transmission of power to great distances, 

 electricity is found to be more economical than either hydraulic, 

 pneumatic, or wire-rope transmission, and comparative tables are 

 given i-howing the first cost of plant per horse-power transmitted, 

 and also the working cost per horse-power transmitted per 

 hour. For a distance of 22,000 yards the cost of ^installation 

 for the transmission of 100 h.p. is ;^87, ;,C3io, ;[^I92, and 

 ;,^i62 per h.p. for electric, hydraulic, pneumatic, and wire-rope 

 transmission respectively ; whilst the cost per h.p. transmitted 

 per hour is 4x8, 6-84, 4*50, and 973 pence. 



Amongst many interesting applications, that made by the 

 Marquis of Salisbury at Hatfield may be specially referred to. 

 The River Lea is utilized to generate electricity by means of 

 turbines, the electricity being transmitted to the house and over 

 the estate for a variety of purposes. The motors at the house 



