C. A, Young on a proposed Printing Chronograph. 99 
Trematocrinus typus Hall. (Cheirocrinus dactylus Hall. 
tuberculosus “ ventricosus 2 
papillatus c amellosus " 
Pentremites Norwoodi Owen & Shum’d.|Belemnocrinus typus White. 
: elongatus Shumard. Bursacrinus Wachmuthi Meek & Wort’n, 
Sayi oe Zeacrinus elegans a 
sirius White. ramosus ' 
Forbesiocrinus Agassizi Hall. perangulatus White. 
asterieformis “ sacculus f 
ramulosus * Troostanus Meek & Worthen. 
Art. XVII—On a proposed Printing Chronograph; by ©. A. 
Youne, Prof. Nat. Phil. and Ast. in Dartmouth College. 
errors very vexatious and hard to trace. 
It is proposed to save the whole of this purely clerical labor 
by making the chronograph itself record the instant of observa- 
tion in hours, minutes, seconds and hundredths of a second, in 
printed characters, and in a form suitable for preservation and 
reduction 
ever, be made much heavier than ordinary, and especially the 
centrifugal fly should be of sufficient size and weight to answer 
the purpose of a balance wheel in preventing sensible changes 
of velocity from slight momentary variations in the resistances 
of the train. a 
The pendulum should be controlled by electro-magnetic im- 
pulses sent every second from the standard clock, in the same 
