A NEW THEORY OF THE SUN. 223 



difference between hydrates and anhydrides should be clearly brought 

 out, and the part which hydrogen plays. After this survey, the pupil, 

 for himself, without prompting, divides the elements into their two 

 great classes. 



Then, after some little study of sulphides and the other binary 

 compounds, the principal acids and bases should be shown in their 

 concentrated form. After this, a number of them should be combined 

 to form salts, and, in doing this, it should be brought out very clearly 

 {by, not for the pupil) how the bases replace the hydrogen of the acid. 

 There should also be some general study of crystallization. 



It would be easy to multiply suggestions, but it has been my pur- 

 pose in this brief paper simply to describe what I have tried, and give 

 only the results of experience. 



o 



A NEW THEOKY OF THE SUN". 



THE CONSERVATION" OF SOLAR ENERGY. 



By C. WILLIAM SIEMENS. 



A PAPER was recently read by me before the Royal Society, 

 under the above title, which may be termed a first attempt to 

 open for the sun a creditor and debtor account, inasmuch as he has 

 hitherto been regarded only as the great almoner, pouring forth inces- 

 santly his boundless wealth of heat, without receiving any of it back. 

 Such a proposal touches the root of solar physics, and can not there- 

 fore be expected to pass without challenge to meet which I gladly 

 embrace the opportunity, now offered to me through the courtesy of 

 the editor of this review, of enlarging somewhat upon the first concise 

 statement of my views regarding this question. 



Man has from the .very earliest ages looked up with a feeling of 

 awe and wonderment to our great luminary, to whom we owe not only 

 the light of day, but the genial warmth by which we live, by which 

 our hills are clad with verdure, our rivers flow, and without which 

 our life-sustaining food, both vegetable and animal, could not be pro- 

 duced. 



When for our comfort and our use we resort to a fire either of 

 wood. or coal, we know now by the light of modern science that we are 

 utilizing only solar rays that have been stored up by the aid of the 

 process of vegetation in our forests or in the forests of former geolog- 

 ical ages, when our coal-fields were the scenes of rank tropical growth. 

 The potency of the solar ray in this respect was recognized even be- 

 fore science had discovered its true significance by clear-sighted men 

 such as the late George Stephenson, who, when asked what in his opin- 



