September 1, 1886.] 



♦ KNOWLEDGE ♦ 



'-'S9 



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of the vapour nor overflow of the oil in the event 

 of the lamp being overturned can occur. Moreover, 

 the oil reservoir, being of metal, is not liable to frac- 

 ture. . . . The light emitted is remarkably white, the 

 flame is perfectly steady, and the combustion is efiected 

 without the slightest odour or smoke." It may be added 

 that the reservoir of ordinary mineral oil lamps ought not 

 to be filled fo the brim, the wick should not quite reach to 

 the bottom of the reservoir, the flame on being first lighted 

 should be turned down low and then gradually raised, and, 

 in extinguishing, the wick ought to be lowered anil a puft" of 

 air sent immediately past the top of the chimney, and not 

 directly down its shaft. If these precautions are taken, the 

 risk from explosions would be practically abolished. 



It has been estimated that an ordinary jet of gas, which 

 consumes five cubic feet per hour, deprives the air during 

 that period of all the oxygen from fitty cubic feet of space, 

 and produces five cubic feet of water vapour, besides a small 

 proportion of smoke carburetted and sulphuretted hydrogen ; 

 but these deleterious products of combustion can be readily 

 removed through the agency of a special tube placed over 

 the gas flame and leading thence to the external atmosphere ; 

 but, of course, such provision has not yet been made for the 

 portable laboratory lamp. 



6 0SJSil}3. 



By Richard A. Proctob. 



I HAVE long felt dissatisfied with what may be called the 

 literature of astronomy, in which we find nothing com- 

 ])arable with the admirable geological works by Lyell, the 

 (Jeikies (especially Alexander), and others. We have works 

 by the surveying astronomers, who preside at national 

 observatories, and who, though admirably skilful in time 

 measurement and in all the processes of mathematical 

 calculation on which the application of astronomy to 

 commerce (the real object of national observatories) depends, 

 have little insight into the philosophy of astronomy, and, 

 indeed, care little for the science in its nobler aspect.s. 

 Then we have works written (generally to order) by those 

 who may be called rather the vulgarisers than the popu- 

 larisers of astronomy. 



On the one hand, specialists, with marvellously exact 

 knowledge of some small department of the science, give us 

 their views — as little satistactory as would be a description 

 of some great cathedral made by a workman who had passed 

 all his time close by some particular pillar. (The pillar may 

 be very necessary, and, perhaps constitute an important 

 feature of the structure, yet it must obstruct, for one who 

 has stood too closely by it, all view of the proportions of the 

 edifice.) On the other hand, we have writings by men who 

 imagine that a suflicient general view of this noble science 

 can be obtained by a few months' study of other people's 

 work. 



* * * 



It has long appeared to me that .^^omething remained to 

 be done for the literature of astronomy, which, so far as I 

 know, no one has yet attempted, viz. : that one who loved 

 the science should devote many years of time to study its 

 general scope, while yet obtaining such suflicient knowledge 

 of its various parts — observational, mathematical, physical, 

 theoretical, and practical — as to be able to picture these 

 correctly, though in due subordination to the general plan. 

 It may be said that this has been done in Herschcl's '• Out- 



lines of Astronomy." Sir John Herschel's book comes 

 nearest, indeed, to my idea of wliat a book on general 

 astronomy should be in order that it may duly instruct and 

 move men's minds — for this, outside its commercial appli- 

 cation, I take to be the great purpose and to constitute the 

 chief value of the science of astronomy. But, greatly as I 

 revere the memory of both the Herschels, father and son, 

 I cannot but recognise in John Herschel's " Outlines " a 

 want of symmetry which mars its worth as a work for 

 instructing the world. There are sections, nay, whole 

 chapters, which seem quite out of place in such a work. 

 The last third of the book is, however, very fine. 



* * * 



Unfortunately Herschel's book is now falling out of 

 date. Astronomy is advancing all the time. It does not 

 require great astronomical discoveries to carry it forward — 

 though, of course, they do so. The advance constantly 

 taking place in our knowledge of physical laws enables us 

 to view astronomical problems with constantly increasing 

 clearness of perception. 



* * * 



Then astronomy, like other sciences, has gained greatlv — 

 perhaps it has gained more than all other sciences — from 

 the growth of men's ideas as to the range of law alike in 

 time and space, (ireatly as the astronomj' of Newton dif- 

 fered from that of Ptolemy (nay, even from that of 

 Copernicus and Kepler), it did not difi'er so much from the 

 earlier astronomy as the astronomj' of our own time, recog- 

 nising laws of evolution and development operating through- 

 out all space and throughout all time, diflers from the 

 astronomy of Newton's time. T/ien the recognition of law 

 in God's universe seemed like setting God on one side in the 

 name of law ; now we find in the doctrine of universal law, 

 operating through periods of time to us practically eternal, 

 and extending throughout what for us is infinity of .space, 

 simply the recognition of perfect congruity between the laws 

 of God and the domain alike in space and in time for which 

 those laws were made. We find in ideas once held to be 

 essential to men's right estimate of Deity a want of all 

 proper recognition of what the Power " working in and 

 through all things " and throughout all time must neces- 

 j sarily be. To us the old ideas, for rejecting which we are 

 thought by the weak-minded to be wanting in reverence, 

 would be .simply blasphemous ; though we admit and feel 

 that respectable person-s who still entertain them are not 

 really wanting in respect for that infinite, though (other- 

 wise) unknowable Power. 



* *■ * 



If it be asked how we can speak of a power as infinite in 

 the same breath in which we speak of it as unknowable, I 

 reply, " As reasonably as we can speak of yonder star as 

 a sun, far vaster and for mightier than this earth on which 

 we live, in the same breath in which we say that the si/ • 

 and might of that star are unknown and (in all probability) 

 unknowable." 



* * * 



The doctrine of evolution, which had its origin in the 

 science of astronomy, is held by the shortsighted folk, who 

 look at all science from without, as something dangerous for 

 the world. I should be very sorry to think any doctrine 

 which I know to be sound, and believe to be on its way to 

 admission as universal as that accorded to the astronomy of 

 Newton, can be dangerous for the world. It must be a very 

 weak, or else a very ill-constructed world, if that is the 

 case. If there is any danger, it must be because of the 

 mL^chievous work of those ignorant fanatics who, in their 

 zeal or their own vain notions, have not been unwilling to 



