Reviev' of Recent (reological Literattu'e. 203 
to the suns raj's. If h^ f)., be the local meridian obliquities, nj, 
n.„ the number of clays, h,, h.,, the total "heat," in the above 
sense, received in summer and winter respectivelj' in each hemi- 
sphere, then the meridian heat secured by that hemisphere on any 
one day may be roughl}' stated as proportional to 
;h, COS. f'l ,,, • „ 1 f lio COS. B, , 
—5 i (IH in summer, and — ^ dn 
111 ^ " ■> 
in winter: and what Herschel sa^'s is not that j hj cos. Hj (Xii — 
j h., cos. a, dn which would correspond to the numbers 63 and 37 
but that hj equals h,,. 
But besides this the meridian heat integrated along the meridian, 
as is done l)y the author, will not give the total heat, which de- 
pends also on the length of the day at the various times and 
places. The total heat received at any latitude is completely 
worked out by Haughton (Trans. Roy. Irish Academy, Vol. 
xxviii), and the integration of his expressions, which ai"e discon- 
tinuous at the arctic circle, can alone give the total heat secured, 
a matter, after all, of little consequence, as it will include the 
tropics which do not enter the question. The numbers G3 and 37, 
therefore, have no significance whatever. The notion that the 
beds of a rock formation have any relation of any kind to glacial 
periods will seem absurd to every field geologist. 
EEYIEW OF EEOEXT GEOLOGICAL 
LITEEATUEE. 
Aiiinds iif Jirifixli (jiolijijij. I'jiuF. J. F. Blake. F. (t. .S. Dulau lS: Co., 
London ; $2.25, 8vo, pp. 404, six plates. This volume contains a record 
of the geological publications in Great Britain during 1891, with an 
appendix for 1S90. It has been compiled by Prof. .T. F. Blake, presi- 
dent of the Geologists' Association of London. More than once 
before the attempt has been made to condut-t such a work, as, for ex- 
ample, by ^Ir. Whitaker, a few years ago, in "The (ieological IJecord," 
but the great cost has prevented permanency. The value of such 
books is unquestionable and needs no words to enforce it to the 
student and the worker. The difficulty of making both ends meet is 
equally certain, if not to all, at least to those who have undertaken 
them. Unless subsidized in some way by learned societies it seems 
improbable, judging from the experience of the past and reasonable 
