Geology and Mineralogy. 229 



(1.) We have terrestial elements in the sun's atmosphere. 



(2.) They thin out in the order of vapor density, all being repre- 

 sented in the lower strata, since the temperature of the solar 

 atmosphere at the lower levels is incompetent to dissociate them. 



(3.) In the lower strata we have especially those of higher 

 atomic weight, all together forming a so-called " reversing layer" 

 by which chiefly the Fraunhofer spectrum is produced. 



The new hypothesis changes these to : 



(1.) If the terrestrial elements exist at all in the sun's atmosphere 

 they are in process of ultimate formation in the cooler parts of it. 



(2.) The sun's atmosphere is not composed of strata which thin 

 out, all substances being represented, at the bottom ; but of true 

 strata, like the skins of an onion, each different in composition 

 from the one either above or below. 



(3.) In the lower strata we have not elementary substances of 

 high atomic weight, but those constituents of the elementary 

 bodies which can resist the greater heat of these regions. - 



Mr. Lockyer discusses at length the variations of spectral lines 

 which are usually regarded as belonging to iron, calcium and 

 other chemical elements, as they appear in the solar spectrum, 

 the solar prominences, the electric spark, .the electric arc and the 

 Bunsen flame. In this comparison of spectra of matter presuma- 

 bly at different temperatures he finds support for his new theory. 

 Also from seven series of solar spots each series containing 100 

 spots, observed mainly by his assistants Messrs. Lawrance and 

 Greening, between 1879 and 1885 he obtains like arguments. 

 Additional ai'guments are obtained from a detailed discussion of 

 the prominence lines, and from the spectra of the corona seen dur- 

 ing eclipses. h. a. n. 



14. Joint Scientific Papers of James Prescott Joule. Published 

 by the Physical Society of London. 391 pp. 8vo. London, 1887. 

 (Taylor and Francis). — The first volume of the papers by Dr. 

 Joule, republished by the London Physical Society, was noticed 

 in volume xxviii of this Journal. The present volume will be also 

 welcome to physicists. It includes a short paper on experiments 

 and observations on the mechanical powers of electro-magnetism, 

 steam and horses, by Dr. Joule and Dr. Scoresby ; a series of 

 papers on atomic volume and specific gravity, and another series 

 on the relation in volumes between simple bodies, their oxides 

 and sulphurets, etc., by Dr. Joule and Sir Lyon Playfair ; finally 

 a series of papers by Dr. Joule and Sir Wm. Thomson, on the 

 thermal effects of fluids in motion. 



II. Geology and Mineralogy. 



1. Note on the Characters and Mode of Formation of the 

 Coral Peefs of the Solomoji Islands, being the results of Observa- 

 tions made in 1882-84; by H. B. Guppy, M.B., F.G.S., during 

 the surveying cruise of H. M. S. " Lark." — Mr. Guppy describes 

 the coral reefs of the Solomon Islands with fulness and much val- 



