OOTOBEB 14, 1910] 



SCIENCE 



513 



^ WraCHELL ON OPHITIC TEXTURE 



To THE Editor op Science : In the proceed- 

 ings of the twenty-first annual meeting of the 

 Geological Society of America, Volume 20 of 

 the Bulletin, pages 661 to 667, Professor A. N. 

 Winchell has a paper upon the use of ophitic 

 and related terms in petrography. Since I in 

 my report for 1909 shall continue to use the 

 term in a somewhat narrower sense than that 

 advocated by Professor Winchell,' a few words 

 of explanation may not be out of place. I 

 shall not plead that publication of the paper 

 was too late to be availed of since Professor 

 Winchell was kind enough to let me read it 

 some time ago. Nor is the argument that one 

 should not change his usage in what may per- 

 haps be the last of my reports of entirely de- 

 termining weight, though in view of the fact 

 that what I have called ophites Winchell 

 would also call ophitic, the point has a cer- 

 tain weight. The facts regarding the early 

 and later use of the term ophitic are fully 

 given by Winchell in the article referred to, 

 with perhaps one exception. That is, in the 

 article from which Winchell cites the original 

 definition of Michel-Levy in the Bulletin of 

 the Geological Society of France, Volume 6, 

 1S78, page 158, only a few pages later (on 

 page 169) he says, " the most characteristic 

 mineral of the ophites is the diallage in the 

 large areas." It seems to me, therefore, very 

 questionable if one should extend the term so 

 as to apply it as Winchell suggests " to all 

 rocks having plagioclase in lath-shaped crys- 

 tals of earlier formations." In fact, it seems 

 to me the petrographically and chemically im- 

 portant thing is the fact that the rock has 

 pretty nearly the composition of a bisilicate 

 and that this bisilicate may be considered as 

 the solvent in which the other constituents are 

 dissolved, from the fluid or molten solution of 

 which they crystallize. One finds, for in- 

 stance, in the quartz diabases, rocks in which 

 the plagioclase is distinctly in lath-shaped 

 crystals of early formation, but in which the 

 matrix is not pyroxene. It seems to me that, 



' The same sense in which it is used by the list 

 of writers cited by him, to which may be added 

 Grout, in Science for September 2, 1910, p. 313. 



as cited by Winchell in the earlier or later 

 definition, a pyroxenic matrix is an essential 

 part of the idea of the ophites. 



I am, however, quite willing to give up the 

 idea that the augite must necessarily be alto- 

 gether in larger grains than the feldspar. In 

 fact, in almost all the so-called ophitic rocks 

 at a proper distance not far from the margin 

 one will find a transition from a glassy inter- 

 sertal or microlitic texture to the coarse 

 ophitic texture, in which the augite acts as 

 matrix to the feldspar, but is so fine grained 

 that several granules may combine in acting 

 as a matrix for a single feldspar. Now this 

 structure would certainly be covered by the 

 original definition as cited by Winchell, in 

 which the size of the augite is not emphasized. 

 But the fact of a pyroxenic matrix seems to 

 me essential to the idea. The extension to a 

 rock in which the pyroxene is replaced by 

 native iron is perhaps an extension by analogy. 

 , Alfred C. Lane 



the reform of the calendar 

 To THE Editor of Science: The sugges- 

 tions of Professor Reininghaus and Doctor 

 Slocum concerning the reform of our present 

 calendar, which were published in Science for 

 June 29 and September 2, are very pertinent 

 and interesting. It is certainly time for some 

 international action looking to the reform of 

 our clumsy calendar. In this connection I 

 beg leave to call attention also to a plan for 

 the reform of the calendar presented last year 

 to the first Pan-American Scientific Congress 

 by Sr. Carlos A. Hesse, of Chili; He sug- 

 gests the division of the year into thirteen 

 months of 28 days each, the new month to 

 follow December and be called Trecember. 

 The extra day (for 13X28 = 364 only), he 

 proposes to call " Zero Day," and it would 

 not belong to any of the fifty-two weeks, or be 

 called by any week day. The extra day in 

 leap years he proposes to call " Double Zero 

 Day," under like conditions. This project is 

 nearly that suggested in the letters in Science 

 referred to above, except that Dr. Slocum's 

 plan (which he ascribes to Mr. Moses B. Cots- 

 worth, of York, England) is to place the extra 

 month in the middle of the year instead of at 



