972 



SCIENCE 



[N. S. Vol. XXV. No. 651 



others in the American Museum in Lane 

 Co., Kansas. 



It measured fourteen feet in length and was 

 eight inches in diameter at its proximal end 

 where it was broken from the upper jaw. Dr. 

 Matthews assures me that it is the largest 

 specimen so far recorded, I regret to say that 

 it was not saved owing to its friable nature. 

 Charles H. Sternberg 



concerning steno 



To THE Editor of Science: It happens to 

 all of us to fancy that what is new to us must 

 be new to the world; and if we fail to look 

 in the right places we do not become disen- 

 chanted. 



The recent reference in Science (May 10) 

 to Steno's noted work on crystallography and 

 a newly-discovered English translation of it, 

 led me to wonder if all the great bibliographers 

 had overlooked the latter. The four authori- 

 ties that came to hand first were Brunet, the 

 British Museum Catalogue, Watts's ' Biblio- 

 theca Britannica ' and Poggendorff's ' Biog.- 

 lit.-VP'orterbuch ' ; all of these include H. O.'s 

 translation of Steno, except Brunet, who has 

 few scientific titles and does not include this in 

 any language. The translation is also cited 

 in the ' Catalogue ' appended to Young's ' Nat- 

 ural Philosophy,' about 1805. 



The guess and conclusion that H. 0. was 

 Henry Oldenburg is confirmed by the article 

 about him in the ' Dictionary of National 

 Biography.' 



This incident will strengthen the views of 

 those who think that a prerequisite to any 

 advanced degree should be a short course in 

 bibliography; for, whatever Pope meant by 

 his lines, they are increasingly true to-day: 



* * * Index-learning turns no student pale, 



Yet holds the eel of science by the tail. 



C. K W. 



Washington, D. C, 

 June 4, 1907 



SPECIAL ARTICLES 

 ON SUN SPOTS 



Apropos of certain recent discussions on 

 solar activity to which I listened with pleas- 

 ure in Philadelphia, I have wondered whether 



a possible analogy between geyser-like action 

 and periodic solar disturbance has been sug- 

 gested. For instance, let the line td in the 

 diagram, represent the distribution of tempera- 

 ture and depth below the solar surface, or, 

 from some points of view, the distribution of 

 temperature relative to pressure. Let the line 

 tp represent the condition of transition, re- 

 ferred to temperature and depth, from an 

 atomic form A to an atomic form B. Below 

 the tp line the element B is stable, above it A 

 is stable. At depths corresponding to c or c', 

 therefore, neither form is persistently stable, 

 but as the spherical shells are thin there need 

 be no marked consequences. To make the en- 

 gine work, two points of intersection, c, should 

 occur. 



I shall assume that the transition of A into 

 B takes place along a doubly inflected intrinsic 

 isotherm for the system AB, after the man- 

 ner explained by James Thomson and Van der 

 Waals. It therefore requires a certain amount 

 of ' supersaturation,' or an excess of heating, 

 to affect the transfer from A to J?, in the ab- 

 sence of special external interferences. I 

 shall also assume that the transfer A to B is 

 accompanied by an evolution of heat, B to A 

 by an absorption of heat, and that the A 

 matter is eliminated from the whole active 

 region by gravitational convection. Finally 

 different atomic forms are arranged between 

 concentric spherical shells, according to their 

 density. 



Suppose, therefore, as a first alternative, 

 that after a sun-spot period, the td line has 

 been depressed by the sudden cooling of all 

 active strata to the position i'd' in Fig. 1. 

 The points c have been displaced towards each 

 other and have quite vanished from the curve. 

 B matter only is present. In the lapse of 

 time, however, the line t'd' again rises to 

 reach td, due to heat arriving from below, 

 within the depths bracketed in the now un- 

 stable state A. It is agreed that the td posi- 

 tion will have to be very closely approached, 

 or a considerable ' supersaturation ' will be re- 

 quired, before another eruption occurs, which 

 drops the td line to t'd' in turn. Whereas 

 the depression of this line is relatively sud- 

 den, its gradual rise together with the prop- 



