380 H. Booth— Utica Slate Graptolites. 
In both particulars we find that B best represents the results, 
and it is the line having the least inclination. We therefore 
conclude that —— is diminishing very slowly. Calculating 
dT 
its equation we find <a = :084 + °0038 s. According to 
this, a can only become zero when s = — 25, or in other 
words the speed of the trotter will only cease to improve when 
he trots a mile in minus twenty-five seconds, or in less than no 
time at all. 
I therefore maintain that Mr. Nipher’s method, if correctly 
interpreted, gives in general the same result as my own. By 
it we may foretell what will be the speed attained fora few 
years in advance, but we cannot tell what will be the ultimate 
speed, nor when it will be reached. 
Institute of Technology, Boston. 
Art. XLIIL.—On the Discovery of Utica Slate Graptolites on 
the west side of the Hudson a few miles north of Poughkeepse ; 
by Mr. Henry Booru. 
DuRING the construction of the West Shore Railroad, on the 
west bank of the Hudson River, the large number of cuttings 
made afforded a good opportunity for examining the slate and 
limestone rocks between West Park and Cornwall. 
t two points small beds of Graptolites were found by Mr. 
C. Lown, of Poughkeepsie, and myself. The localities were 
nearly obliterated by the workmen, but we obtained some specl- 
ich were referred to Professor R. P. Whitfield, of 
New York. Enclosed is his letter, giving the names of the 
graptolites submitted to him. 
he localities are, one at Blue Point, about two miles south 
of New Paltz Landing (now called Highland), and one about 4 
mile north of the same place. 
Poughkeepsie, N. Y., Sept. 29th. 
Copy of Letter from Mr. R. P. Whitfield, dated American 
Museum, New York, August 28th. 
I find among the Utica Slate Graptolites sent me, Diplograptus 
pristis Hall (not of Hisinger); Chimacograptus bicornis all ; 
Dichograptus furcatus Hall; D. divaricatus Hall?; Monograptus 
ae ll; M. sagittarius Hall, and Diplograptus marcedus 
