7. Locke on the Electro-Chronograph. 235 



and especially when that friction taxed, either directly or indi- 

 rectly, the motion or force of the pendulum : especially did I 

 consider it incompatible with astronomical clock performance, 

 that the contact should be a direct friction on the pendulum. 



The above-named elementary inventions remained unapplied until 

 1848-9. 



9. In October, 1848, Coast Surveying Assistant, Sears C. 

 Walker, who had some years been determining longitude by 

 means of electric telegraphs, the "time signals'' and "star sig- 

 nals" being made by ordinary clock reading and by manual con- 

 tacts and breaks of the electric circuit, thereby bringing the dis- 

 tant magnet into visible and audible action, applied to me to im- 

 prove the means of determining longitude. He pointed out two 

 desiderata — one, a means by which the clock itself should close 

 and break the circuit, and thus make its beats audible through 

 the means of a distant included electro-magnet — and the other, 

 a means by which an observer at one point of a telegraphic cir- 

 cuit of wires might start a clock at repose, at any distant part of 

 that circuit, at any desired moment. 



10. The former, I informed Mr. Walker, had already been ac- 

 complished by the magnetic clocks of Europe, a fact of which 

 he did not appear to have been specifically apprised. To accom- 

 plish the latter, I devised the means, a thing very easy to be 

 done. I informed him also that I had objections to the mode of 

 action, so far as I understood it, by which the electrical clocks 

 produced their effects, and I was of opinion I could improve them 

 by limiting my invention by the following conditions, which had 

 occurred to me four years before, viz. : 1st, That nothing should 

 interfere in the least with the pendulum, and 2d, That the elec- 

 trical current should pass through no part of the proper clock. I 

 applied my tilt hammer of 1844, and succeeded quite to my satis- 

 faction. The most agreeable point was, that on trial it appeared 

 that the electric attachment to my astronomical clock did not 

 change fa the least its rate of going. This attachment caused 

 the electro-magnet to reciprocate audibly and visibly, and would 

 have caused a proper magnetic clock to be moved secondarily at 

 the greatest distance to which the wires extend. It fulfilled ad- 

 mirably the conditions suggested by Mr. Walker. But this in- 

 dention, thus cleared of frictional contact and of interference 

 with the pendulum, was still a mere magnetic clock and not a 



chronograph." In the course of my experiments it occurred 

 t0 me that by combining two other instruments with this clock, 

 v, z. : the Morse's Register * or its equivalent, and a break-circuit 



* The term a Regis' " hen* and in several other places, is used to mean Ihe dock- 

 hke machine which carries forward the fillet o( paper, while the magnet in Mane's 



fciaehin 



