JuxE 22, 1883.] 



♦ KNOWLEDGE ♦ 



379 



wliic}) new hooks were in some cases necessary. Moreover, 

 Mr. Urquliart had made some reputation by his previous 

 works on electro-metallurgy. 



The work is unambitious in design, and accordingly no 

 pretence is made to deal exhaustively with the subject 

 Nevertheless, it is difficult to perceive the reason animating 

 the author to exclude all reference to electrical measure- 

 ment, oven to definitions of the various units and everj-day 

 technicalities, in favour of long descriptions of various 

 liatteries, some of which are useless for electric light pur- 

 poses, and the adoption of which cannot fail to terminate 

 in disaster and disappointment Our difficulty is to 

 discover for what special class of readers the 

 work is intended. If for electricians, the work 

 is somewhat feeble ; if for amateurs, there is a 

 great deal that can in no way interest them. If on 

 the otlier hand, as indeed seems most probable, the work 

 is intended to be a sort of handbook for professional men : 

 architects, builders, gasmen, vestrymen, and so forth, the 

 general arrangement appears to have been sadly cared for. 

 This latter class of readers could have well spared tlie 

 greater part of the 44 pages devoted to batteries, while 

 the information about machines and lamps is far too 

 scanty to be of much practical use. Jleagre also is the 

 information upon general construction, and a telegraph 

 lineman would be justiried in smiluig at the picture of the 

 " Britannia " joint. 



Secondary batteries are summarily dealt with in four 

 pages. The chapters on magnets and dynamo machines 

 contain good and generally relialile information, the fault 

 being in the choice and arrangement of matter. Machines 

 which are now out of date, and which, when made, involved 

 no new or important feature, are allowed ample spare ; 

 while more modern, and at the same time more im- 

 portant ones are dismissed with two or three lines 

 and a reference to some other source of information. 

 Thus of the Gulcher machine, which is probably 

 one of the best in the market, all that is said 

 is : — " This machine bears some resemblance to the 

 Brush apparatus. It will be found described in 

 the Electrician, of Oct 29, ISSl. One machine develops 

 an electromotive force of 70 volts, the other of 2,000." It 

 i-i pleasing to notice that the Ferranti (spelt Farranti on 

 every occa.sion) comes in for a share of attention, but it 

 would have looked better had the author refrained from 

 making so many advertising observations on this and other 

 dynamos. 



In the seventh chapter, containing " general observations 

 on machines," we are told that " if there is jumping or 

 flickering of the light, the carbons are bad, or the same 

 defect may be caused by the engine not having a 

 sufficiently sensitive governor to keep up a steady 

 motion." This is true, so far as it goes ; but surely 

 the lamp itself has something to do with steadiness, 

 otherwise whence is the perfection of the Fyfe-Main lamp 

 (which, by-the-way, does not meet with any attention at 

 the hands of Mr. Urquhart) ■? Some interesting informa- 

 tion concerning the history of the construction of incan- 

 descent lamps is imparted, although a slight error or two 

 still exists. Such, for example, as the resistance of a Swan 

 lamp, which is stated to be 150 ohms when hot and 250 

 ohms when cold, or about five times the actual resistances. 

 A work on the electric light without the description of a 

 single meter is a somewhat anomalous phenomenon, and it 

 is to be hoped that, should a third edition be issued, some 

 attention will be devoted to this Ijranch of the subject 

 The paper and printing are good ; the diagrams, too, are 

 highly commendable, if we except one or two of them for 

 bad perspective (as in the illustration of Ladd's machine). 



On the whole, the work is very readable. It is infinitely 

 superior to the work on " Electromotors," by the same 

 author, and will doubtless hold a place in the literature of 

 electrical science for some time to come. 



THE FACE OF THE SKY. 



From Jcxe 22 to Jily 6. 



By F.R.A.S. 



rpHE eun still continues to develop interesting little groups of 

 I spots, as well ns faculse, &c. (ut less frequent intervals, how- 

 ever, than of late) and should hence be observed with the telescope 

 whenever ho is visible. The aspect of the stellar vault will be found 

 depicted on Map VI. of "The Stars in their Seasons;" but, as we 

 remarked a fortnight ago, there is no real night, during the period 

 over which these notes extend, in any part of the United Kingdom. 

 As far as planets are concerned, the sky is a practical blank for the 

 observer. Nor do any occultations of stars by the moon occur 

 during our specified period. Her ago on Jane 22nd at noon is 17'2 

 days, and, pretty obviously, on July 4th, 292 days. .\t noon 

 on" July 5th her age will be 09 day, and, of course, 19 

 on the 6th. Hence she will be out of the reach of the 

 ordinary observer after the night of the 2oth. On the 22nd she 

 is in Sagittarius, passing into Aquarius during the afternoon of 

 the 23rd. She continues in that constellation during the whole 

 of the 2-ith and the greater part of the 25th, travelling into 

 Pisces before noon on the 20tli. She remains in I'isces during the 

 27th and 2Sth; and about 11a.m. on the 29th will be found in 

 that region of the sky where Pisces, Cetus, and Aries are conter- 

 minous. She is in Aries during the 29th and a good deal of the 

 30th, travelling into Taurus about 2 a.m. on July 1. There she 

 remains until noon on July 3rd, when she crosses the boundary into 

 the northern part of Orion. Traversing this in the course of the 

 next twelve hours, we find her at midnight in the confines of 

 Gemini. She continues in Gemini until 3 p.m. on the 5th, at which 

 time she moves into Cancer, where we leave her on July 6th. 



M. BoussiN'GAULT has recently presented to the French 

 Academy a communication on the matter difl'used or sus- 

 pended in the air at great elevations. lie has e.xamined 

 samples of the rain and snow which fell on the Alps from 

 1859 to 1865, and has found nitric acid varying from to 

 069 mgs. per litre of water examined. The sample con- 

 taining the largest amount of nitric acid also contained 

 3 mgs. of ammonia. He intends soon to compare the 

 electrical condition of the northern and southern hemi- 

 spheres, which condition probably aflfects the amount of 

 nitrogen compounds present in the air and even in the 

 soil. The writer also, says the Journal of the Society of 

 Chemical Industry, notes the fact that hailstorms may 

 occur in very elevated mountain regions, he having ex- 

 perienced one in the province of Riobamba at a height of 

 5,000 metres above the sea level. 



Allots of metals are often difficult to make and very 

 small quantities greatly afJ'ect alloys. The presence of yrruo^ 

 of a pound of antimony in a pound of melted lead increases 

 the rapidity with which the lead oxidises and burns. Lead 

 which contains more than ,-^,',,,17 °f its weight of copper is 

 unfit for the manufacture of white lead. Der Techniker 

 says gold with an alloy of t7v,',,77 of lead is extremely brittle. 

 Copper w-ith }, per cent, of iron has only 40 per cent, of the 

 electric conductivity of pure copper. Xickel was regarded as 

 a metal which could be neither rolled, hammered, nor welded, 

 until it was found that the addition of yr.'uTy of magnesium, 

 or i„'„„ of phosphorus, makes it malleable. Some varieties 

 of cast steel are exceedingly brittle, but the addition of yV 

 of 1 per cent of magnesium makes them malleable. At 

 the Paris Exposition of 1878 a great ditlerence was found 

 in the toughness of sheets which were made of Swedish 

 puddled iron. The only difierence which chemical analysis 

 showed was that the good plates contained nj-uCoui ^^^ 

 the bad 777 J^uu of phosphorus. 



