Polytechnic Association. 569 



electro-magnet ; but the cost and trouble of keeping up a large bat- 

 tery for this purpose, led us to do all the work mechanically, only 

 using electricity as the governing power. Accordingly, a heavy run- 

 ning gear was built for raising the hammer, capable in its present 

 form of delivering 800 blows without winding ; and it can be readily 

 moditied to give ten times that number, if desirable. This gearing is 

 entirely detached from the hammer when elevated, but is unlocked 

 just before the hammer reaches the type, immediately raising it again. 

 The time consumed for this operation is about three- tenths of a second, 

 allowing, therefore, observations to follow each other at a minimum 

 interval of one-half second. When the hammer is elevated it is 

 locked by an electro-magnet, the operating of this magnet allowing 

 it to fall and print. The armature time of the hammer is about 0.07 

 seconds, being but little in excess of our ordinary chronographic 

 recording pen. 



The type are inked by means of small rollers, covered with cloth, 

 resting against their rim, and revolving with the wheel by friction. 

 These rollers require inking every two or three days. If desirable, 

 the inking rollers may be dispensed with, and impression paper used 

 instead. After numerous experiments made with both methods, we 

 have preferred the ink. 



The paper fillet, two inches in width, is wound on a small spool, 

 holding about forty feet, and drawn between two rollers, the same as in 

 a Morse Register. Every time the hammer falls', the fillet is advanced 

 about one-quarter of an inch, by the action of an escapement driven 

 by a weight. One spool of paper will hold about 1,200 observations, 

 including the spacing for different objects. The same escapement is 

 also operated by an electro-magnet, under the control of the observer, 

 who by pressing a key is able to make spaces of any width between 

 the prints. 



The train carrying the minutes and integer seconds will run eight 

 hours ; the gear for elevating the hammer will deliver 800 blows ; and 

 the train for moving the paper fillet will go 1,200 times without 

 winding. The fast moving train runs one hour and thirty-six 

 minutes ; but since this train can be stopped at pleasure, without 

 changing the zero of the type, its comparatively brief running is not 

 a serious inconvenience. 



To recapitulate, we claim the following principal points: 1st. Sep- 

 arate movements for the integer seconds, and the hundredths oi 

 seconds; 2d. The method of regulating the hundredths of seconds 

 wheel, by an electro-magnet in connection with the standard clock: 



