572 



SCIENCE. 



[N. S. Vol. IV. No. 94. 



tween the Block Island strata and those of Long 

 Island and the islands to the eastward was 

 commented upon by them and by others. If 

 the article in question went no further than this 

 it would attract but little attention. The con- 

 clusions which the author draws, however, are 

 so startling that they require the earnest con- 

 sideration of everyone who has ever had any 

 experience in the geology of the region. 



For example : ' 'The well-known clay deposits 

 of Long Island I have not carefully examined 

 in place. There is much in the published descrip- 

 tion of them, however, to indicate that they may 

 represent some of the same Jurassic beds.'" 



Inasmuch as the present writer thought that 

 the Cretaceous age of the clays at Glen Cove, 

 Northport, etc., had been thoroughly proven 

 and the Tertiary age of others had at least been 

 satisfactorily indicated,* the above surmise is 

 highly interesting and any proofs of their Ju- 

 rassic age are anxiously awaited. 



Again, "The clay bluffs at Gay Head, in Mar- 

 tha's Vineyard have many characteristics of 

 the same series, but the presence of Cetacean 

 remains in one portion of them indicates that this 

 is Tertiary. There ai*e, however, some reasons 

 for supposing that the most of the clays are 

 much older, and I believe that they contain repre- 

 sentatives of the same great Jurassic formation. ' ' 



As these deposits have been amply proven, 

 by David White,! Merrill, % Shaler, § and the 

 writer, \\ to consist of Cretaceous and later strata, 

 the expression of a mere belief in regard to 

 their Jurassic age seems somewhat superfluous. 



In a postscript the author says that since his 

 article was in print he has visited Long Island 

 and Martha's Vineyard, and states : "On Mar- 

 tha's Vineyard I found that the great series of 

 variegated clays forming Gay Head, and gener- 



* Trans. N. P. Acad. Sci., xii. (1893), pp. 222-337; 

 ibid. xiii. (1894), pp. 122-129. Brill. Torr. Bot.Club, 

 xxi. (1894), pp. 49-65. Trans. JSf. Y. Acad. Sci., xv. 

 (1895), pp. 3-10. 



■f Am. Journ. Sci., xxxix. (1890), pp. 93-101; Bull. 

 Geol. Soc. Am., i. (1890), pp. 554, 555. 



t Trans. N. Y. Acad. Sci., iv. (1885), pp. 78, 79. 



^Bull. Mus. Camp. Zool., xvi., No. 5 (1889), pp. 

 89-97. 



II Trans. N. Y. Acad. Sci., xiii. (1893), pp. 8-22; 

 Bull. Geol. Soc. Am., vii. (1895), pp. 12-14. 



ally regarded as Tertiary, are certainly Mesozoic, 

 and all apparently Jurassic." 



In view of what has already been proven, the 

 above statement is the most surprising of all, 

 and as he concludes with the promise, ' ' I hope 

 soon to discuss this subject more fully else- 

 where," the appearance of the discussion is 

 looked for with great interest. 



[The italics in the text are mine. A. H.] 



Arthur Hollick. 

 Department of Geology, 



Columbia University. 



the curve-tracing top. 

 In reply to Mr. C. B. Warring' s suggestion 

 of smoked surfaces, I would say that two of my 

 students have for some time been engaged in 

 computing the moment of inertia of the top from 

 its mass, the radius of the point, the dip, the 

 instantaneous period of precession and the dif- 

 ference of the cardinal radii of curvature of the 

 curves drawn very nearly the maximum dis- 

 tance between two consecutive spires. They 

 have tried lampblacked surfaces, but have given 

 them up because the substance is apt to flake 

 off at sharp angles and the curves are not satis- 

 factory. Mr. Warring' s own design bears this 

 out. Moreover, Mr. Warring seems to have 

 missed the point of my article. I value the 

 result in proportion to the simplicity of the 

 means employed. To use lampblack and var- 

 nish is to go much out of one's way. 



C. Barus. 

 Brown University, Providence, E. I. 



NEW APPLES. 



To THE Editor of Science : As a contribu- 

 tion to your freak apple discussion in your issue 

 of September 4th, where the phenomenon is de- 

 scribed as a pollen phenomenon, and continued 

 in your issue of October 2d, I send the following 

 cutting from John Lewis Child's Fall Catalogue 

 of 1896: 



' ' Two-Faced — We never brought out a more unique 

 novelty than this. It originated in Cayuga county, 

 N. Y., and the original tree has been known for many 

 years, but this is the first time it has ever been 

 propagated and put upon the market. The tree hears 

 an apple which is in size and shape similiar to the 

 Tallman Sweet ; its peculiarity being that every fruit 



