NA TURE 



1'3 



THURSDAY, AUGUST 2, 1894. 



LORD KELVIN ON GENERAL PHYSICS.^ 

 Popular Lectures and Addresses by Sir William 

 Thomson {Baron Kelvin), P.R.S., LL.D., D.C.L., a^c. 

 In three volumes. Vol. II. "Geology and General 

 Physics.' With illustrations. N.\ture Series, pp. 

 X. + 599, with index. (London and New York : Mac- 

 millan and Co., 1894.) 



II. 



AT the present time, when the need for a fully-equipped 

 and well-manned National Physical Laboratory for 

 expensive and for secular observations is sometimes 

 discussed, it is interesting to quote from Lord Kelvin's 

 Presidential address to the British Association at 

 Edinburgh in 1 871 as follows : — 



" The success ofthe Kew Magnetic and Meteorological 

 Observatory affords an e.^iample of the great gain to be 

 earned for science by the foundation of physical observa- 

 tories and laboratories for experimental research, to 

 be conducted by qualified persons, whose duties 

 should be, not teaching, but experimenting. Whether 

 we look to the honour of England, as a nation which 

 ought ahvays to be the foremost in promoting physical 

 science, or to those vast economical advantages which 

 must accrue from such establishments, we cannot but 

 feel that experimental research ought to be made with us 

 an object of national concern, and not left, as hitherto, 

 exclusively to the private enterprise of self-sacrificing 

 amateurs, and the necessarily inconsecutive action of our 

 present Governmental Departments and of casual Com- 

 mittees." 



" On the Continent there exist certain institutions, 

 fitted with instruments, apparatus, chemicals, and other 

 appliances, which are meant to be, and which are made, 

 available to men of science, to enable them, at a moderate 

 cost, to pursue original researches." 



" The physical laboratories which have grown up [in 

 Universities] show the want felt of Colleges of Research ; 

 but they go but infinitesimally towards supplying it, 

 being absolutely destitute of means, material or personal, 

 for advancing science except at the expense of volun- 

 teers, or for securing that volunteers shall be found to 

 continue even such little work as at present is carried 

 on." 



And in connection with the still urgently pressing need 

 for a systematic abstract of papers and of a central com- 

 prehensive report of annual progress in physics, such as 

 is already satisfactorily accomplished by our friends the 

 chemists, the following quotation from the same address 

 is likewise of interest : — 



"A detailed account of work done and knowledge 

 ;.;ained in science Britain ought to have every year. The 

 Journal of the Chemical Society and the Zoological Record 

 do excellent service by giving abstracts of all papers pub- 

 lished in their departments. The admirable example 

 afforded by the ("/erman Fortsc/tritte ^.nd Jaliresbcricht is 

 before us ; but hitherto, so far as 1 know, no attempt has 

 been made to follow it in Britain. It is true that several 

 ofthe annual volumes of the /a/uesiericlit were translated, 

 but a translation . . . cannot supply the want. An inde- 

 pendent British publication is for many obvious reasons 



' (Contin icj from page 293.) 



NO. 1292, VOL. 50] 



desirable. The two publications, in German and English, 

 would, both by their differences and their agreements, 

 illustrate the progress of science more correctly and use- 

 fully than any single work could do." 



From the same address I cull the following detached 

 morsels : — 



"Our knowledge of the dark lines is due to Fraun- 

 hofer. Wollaston saw them but did not discover them." 

 " The old nebular hypothesis supposes the solar system 

 .... to have originated in the condensation of fiery 

 nebulous matter. This hypothesis was invented before 

 the discovery of thermodynamics, or the nebula: would 

 not have been supposed to be fiery." 



In amongst the more geological portion of the book 

 there comes a Presidential address to the Society of 

 Telegraphic Engineers, from which it may be useful to 

 extract the following compact statements concerning 

 atmospheric electricity : — 



" In fair weather the surface of the earth .... is 

 always found negatively electrified. . . . The more com- 

 mon form of statement is that the air is positively 

 electrified, but this form of statement is apt to be 



delusive The surface of the earth is negatively 



electrified, and positive electrification of the air is merely 

 inferential, .... the lower regions of the air [such air 

 as comes in through windows] are negatively electrified. 

 . ... It is not always negative, however. I have found 

 it positive on some days. In broken weather .... it 

 is sometimes positive and sometimes negative. Now 

 hitherto there is no proof of positive electricity in the air 

 at all in fine weather ; but we have grounds for inferring 

 that probably there is positive electricity in the upper 

 regions of the air." 



Opening the book now at page 360, we find a paper 

 which might well have been included in the volume on 

 " Navigational Affairs," being on the subject of the Rate 

 of clocks and chronometers as influenced by the mode 

 of suspension. It is rather surprising to learn that the 

 rough and ready conditions of a pocket by day and a 

 pillow by night give a watch a better chance of going 

 correctly than many other modes of support, such as 

 hanging on a nail or even lying flat on a table. If a 

 correctly-going watch be hung up by a single long thread 

 normal to its plane it begins to gain, and if its case 

 has ^l times the moment of inertia of the balance-wheel, 

 it gains one in 2« swings ; a watch actually tried, whose 

 n was 650, gained more than a minute (67 seconds) in a 

 day when so suspended. Suspend it by a bifilar sus- 

 pension and gradually move the threads further apart, so 

 as to increase the natural rate of swing of the case, and 

 the watch gains more and more, until, when the periods 

 of case and wheel coincide, it gains furiously, and then 

 either stops altogether or else begins to lose ec[ually 

 furiously. Separate the threads a little mor2 still, and 

 the losing rate begins to diminish, until ultimately, when 

 the constraint is great, it begins to keep correct time 

 again. Thus by suspending a chronometer judiciously 

 it can be adjusted to time without touching the hands ; 

 but if it be suspended so as to have a quick natural 

 period of swing, it cannot be expected to keep good 

 time. If placed on a cushion to protect it from jars, 

 its case is not unlikely to have a quick swing-period ; 



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