VI NOTES BY THE EDITOR 



into collision, and thus that their heat and light are revealed by the 

 telescope ? Mr. Huggins's observations go to show that in some, at 

 least, of these nebulae there is no solid matter at all. Herschel has 

 stated that the mass of one of these planetary nebula?, if distant from us 

 as far as 61 Cygni, would fill a space equal in diameter to seven times 

 that of the orbit of Neptune ; and hence, were it not that the light 

 was concentrated nearly into a single line, its examination would not be 

 practicable. In the light of these nebulas, as is shown elsewhere, 

 there is nothing to indicate, as in the case of the sun, a solid luminous 

 globe, behind the luminous photosphere, but the light from them is such 

 as is characteristic of gaseity. When a star occurred in, or was asso- 

 ciated with, the nebulae, a very feeble continuous spectrum was 

 observed. To understand fully the researches which have led to Mr. 

 Huggins's conclusions, the reader would do well to refer to the expla- 

 nations of the process of spectrum analysis as detailed in the volumes of 

 the Annual of Scientific Discovery for 186:?. '6,3, and '64 ; there being 

 at the present time no continuous and complete published record of 

 these investigations. 



The 34th annual meeting of the British Association for the Advance- 

 ment of Science, was held at Bath, England, and was very largely 

 attended by British and foreign scientists. The annual address of the 

 President, Sir Chas. Lyell (republished in full in this volume), was, 

 in the main, a popular discussion of the .most recent geological re- 

 sults and theories, and cannot fail to be read with interest. 



At this meeting a Committee of the Association, consisting of Lord 

 Wrottesley, Sir W. Armstrong, the Astronomer Royal, the Master of 

 the Mint, 1'rof. Leon Levi, Mr. W. Ewart (Chairman of a similar 

 committee in the House of Commons), and other distinguished gen- 

 tlemen, reported in favor of adopting the metric system (of weights 

 and measures) of France, and the report was unanimously adopted, 

 yet with some discussion as to whether the unit should be the French 

 meter or not. Among the recommendations of the Committee, were 

 the following : 



That it is desirable, in the interests of science, to adopt a decimal 

 sy>tem of weights and measures. That in furtherance of this proposal 

 it is desirable, from its scientific capabilities, to adopt the metric sys- 

 tem. That it be recommended to the Government, in all cases in 

 which statistical documents issued by them relate to questions of inter- 

 national interest, to give the metric equivalents to English weights and 

 measures. That in communications respecting weights and meas- 

 ures, presented to foreign countries which have adopted the metric 

 system, equivalents in the metric system be given for the ordinary 

 English expressions for length, capacity, bulk, and weight. That it 



