August 29, 1884.] 



SCIENCE. 



179 



9 pi.), is in the main devoted to developing a 

 new system of classification for the group, and 

 to the criticism of Professor Haeckel's mono- 

 graph, ' Die kalkschwamme.' 30 species were 

 brought in by the Challenger, 23 of which were 

 new. All these are elaborately described, 

 and illustrated by most exquisite plates, chiefly 

 drawn by the author. Mr. Poljaeff expresses 

 the hope, " that the systematic arrangement of 

 the group Calcarea, here proposed, will serve 

 as a sufficiently sure basis for further investi- 

 gations," — a hope which will be shared by 

 all, but which in the present unsettled state of 



opinion among specialists in this department, 

 and in view of the scarcit}' of material for 

 investigation, is perhaps a trifle premature. 



Other papers upon the Protozoa are prom- 

 ised, but are mostly far down in the list. The 

 Hexactinellid sponges are assigned to Prof. 

 F. E. Schulze ; the Tetractinellidae, to Pro- 

 fessor Solles ; the Monactinellidae, to Mr. S. 

 O. Ridley. Mr. H. B. Brady's paper on the 

 Foraminifera, and Professor Haeckel's on the 

 Radiolaria, will probably first be printed. 



G. Brown Goode. 



Smithsonian institution. 



BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 



RECENT PROGRESS IN PHYSICS. 1 



After referring to what at first appeared a rather 

 startling experiment, the holding of a meeting of 

 the association outside of Great Britain, and to the 

 undoubted pleasure and benefit the members would 

 receive from their visit to Canada, Lord Rayleigh 

 spoke of the loss the association had met in the death 

 of Sir W. Siemens, and gave a brief account of Sie- 

 mens' s scientific work. He called attention to the 

 fact that it is now some years since the presidential 

 chair had been occupied by a physicist, and, while 

 regretting that he should be called on to preside when 

 the association met in a country of so great interest to 

 the naturalists, he proposed to do the best he could 

 by giving a sketch of the progress in late years of 

 physical science. 



It is one of the difficulties of the task, that subjects 

 as distinct as mechanics, electricity, heat, optics, and 

 acoustics, to say nothing of astronomy and meteor- 

 ology, are included under physics. Any one of these 

 may well occupy the lifelong attention of a man of 

 science; and to be thoroughly conversant with all 

 of them is more than can be expected of any one 

 individual, and is probably incompatible with the 

 devotion of much time and energy to the actual ad- 

 vancement of knowledge. Another difficulty incident 

 to the task, which must be faced but cannot be over- 

 come, is that of estimating rightly the value, and 

 even the correctness, of recent work. It is not 

 always that which seems at first the most important 

 that proves in the end to be so. The history of 

 science teems with examples of discoveries which 

 attracted little notice at the time, but afterwards 

 have taken root downwards, and borne much fruit 

 upwards. 



One of the most striking advances of recent years 

 is in the production and application of electricity 

 upon a large scale. The dynamo-machine is, indeed, 



1 Address to the British association for the advancement of 

 science at Montreal, Aug. 27, 1884, by the Right Hon. Lord Ray- 

 leigh, H.A., D.C.L., F.R.S., F.R.A.S., F.R.G.S., professor of 

 experimental physics in the University of Cambridge, president 

 of the association. 



founded upon discoveries of Faraday, now more than 

 half a century old; but it has required the protracted 

 labors of many inventors to bring it to its present 

 high degree of efficiency. Looking back at the mat- 

 ter, it seems strange that progress should have been 

 so slow, not merely in details of design, the elabora- 

 tion of which must always require the experience of 

 actual work, but with regard to the main features of 

 the problem. It would almost seem as if the diffi- 

 culty lay in want of faith. Long ago it was recog- 

 nized that electricity derived from chemical action is 

 (on a large scale) too expensive a source of mechani- 

 cal power, notwithstanding the fact that (as proved 

 by Joule in 1846) the conversion of electrical into 

 mechanical work can be effected with great economy. 

 From this it is an evident consequence that electri- 

 city may advantageously be obtained from mechani- 

 cal power; and one cannot help thinking, that, if the 

 fact had been borne steadily in mind, the develop- 

 ment of the dynamo might have been much more 

 rapid. But discoveries and inventions are apt to 

 appear obvious, when regarded from the stand-point 

 of accomplished fact ; and he drew attention to the 

 matter only to point the moral that we do well to 

 push the attack persistently when we can be sure 

 beforehand that the obstacles to be overcome are only 

 difficulties of contrivance, and that we are not vainly 

 fighting unawares against a law of nature. 



The present development of electricity on a large 

 scale depends, however, almost as much upon the 

 incandescent lamp as upon the dynamo. The suc- 

 cess of these lamps demands a very perfect vacuum, 

 — not more than about one-millionth of the normal 

 quantity of air should remain, — and it is interesting 

 to recall, that, twenty years ago, such vacua were 

 rare even in the laboratory of the physicist. It is 

 pretty safe to say that these wonderful results would 

 never have been accomplished had practical appli- 

 cations alone been in view. The way was prepared 

 by an army of scientific men, whose main object 

 was the advancement of knowledge, and who could 

 scarcely have imagined that the processes which they 

 elaborated would soon be in use on a commercial 



