Feb. 17, 1882. J 



• KNOWLEDGE • 



335 



In pay for c.rpedilions to Possession Island and other 

 ji'a-es in the dangerous Antarctic seas, and to provide /or 

 stations to be occitpied there diiriii;/ the tran.'rit of next 

 December. It was this pot plan of his which Sir George 

 Airy was really giving up, when ho explained to the 

 Government that Antantic stations were " geographically 

 unsuitable," and so forth. 



It is a fa\ourite argument of the junior officials who 

 tried to earn approval from their chief by attacks on extra- 

 officials like Sir E. Beckett and myself, that Sir 0. Airy 

 never did yield as to the stations for observing the whole 

 transit. It is not quite true. He yielded in the case of 

 the Indian stations, which astronomers of other countries 

 were not likely to occupy. 1 think too highlj' of his real 

 zeal for science to suppose he would not have yielded in 

 the case of Siberian and North Chinese stations, if 

 America, llussia, Germany, and France, by occupying the 

 stations he had overlooked and later stigmatised as useless, 

 Jiad not saved him from the concession. 



Like all that Sir George Airy has ever done in this way, 

 the record of the observations made by the various parties 

 is exceedingly well arranged. His labours here would have 

 served to very much more than retrieve what, after all, was 

 in its inception but an unlucky mistake (which might 

 easily have been corrected, and the world none the wiser, if 

 he had not been so needlessly impatient of extra-official 

 suggestions). Sir George Airy shows himself in the body of 

 this work what he has shown himself during his whole 

 tenure of office, the most energetic and laborious of our 

 Astronomers Royal. If he had left out all reference to 

 the discussion of 1809-187.'^, or if, referring to it, he had 

 told the whole story, this would have l)een all I need have 

 said ; but I ha\c not thought it Just, either to myself or 

 those who by their aid ensured the adoption of proper 

 measures for observing the transit of 1^71, to allow an 

 imperfect and entirely misleading account of the matter to 

 remain uncorrected — though I know very well that for one 

 who might be misled by Sir (A. Airy's inexact account, 

 thousands (including himself) know how the matter really 

 ^tat\ds. It seems almost incredible that the writer of this 

 I' -ount should bo the same man who so frankly and 



ol)ly acknowledged his error in the Adams-Leverrier 



introversy. 



THE CRYSTAL PALACE ELECTRICAL 

 EXHIBITION. 



Second Xotick. 



I^IIOSE who can look beneath the surface will see that 

 during the past week some considerable progress has 

 been made towards completing the exhibits. To a cursory 

 examiner, however, but little improvement can be apparent. 

 A few Jabloehkofl" lamps (Compaffuie Ginerah; d'Electricite) 

 *re lighted, Init present a poor appearance when compared 

 with the other systems. The four Cromptons which light 

 the space in front of the stage are also far from satis- 

 factory. We may hope to see something better in the 

 telephone section during the next week or so. 

 We will now give a description of 



The Brvsii System 



of electric lighting. In the machine room, as mentioned 

 last week, arc a number of generating machines, which, 

 when all in work, will be driven by five steam-engines, two 

 of them of 20-horse-power, two of .30-horse-power, and one 

 of 25-horsp power. The latter is the only one at present 

 fitted up. It is working up to about 45-horse-power, and 



drives three of the generating machines, two of which 

 maintain between them thirty-two arc light.s, and the other- 

 about fifty incandescent lamps. The third machine i.s, 

 however, capable of supplying the current for as many as 

 150, or perhaps 200 lamps. 



The lamps are very simple in construction, requiring no 

 adjustment aft«r being once put in ord -r. Fig. 1 is one 



of the ordinary forms which will burn uninterruptedly for 

 eight hours. The carbons are made in 1 2-in. lengths, and 

 when the lamps are required for more than eight hours 

 together, they are furnished with a double or even treble 

 supply of carbons, the current passing from one pair to 

 another automatically. Fig. 2 is a somewhat rough 



D^-=Q 



diagram ilhustrating the principles and action of the lamp. 

 The current enters at X, and at )' splits into two sections, 

 each of which passes through a small coil of thick wire 

 ////', and on leaving the coils the currents combine again 

 and pass to the upper carbon rod ; thence through the arc 

 to the lower rod, and out at Y. From X there also passes 

 a thin wire which is coiled many times round // //' outside 

 the thick wire. These thin coils are wound in series, and 

 on both bobbins they arc in opposition to the thicker coils. 

 The thin wire then passes several times round another 

 bobbin T, carrying a small coil of thick wire wound in 

 the satnt direction. The circuit is completed by a wire 



to r. 



The lever, A B, is in metallic connection with the positive 

 pole, and carries a small button, M', over which, but not 



