208 Application of the Galvanic Circuit 



Wheatstone's electro-magnetic clock, undertook to make a series 

 of experiments on the subject. He succeeded, on the 6th of 

 November, in inventing a method which like the former, is found 

 to be perfectly successful in practice, and free from danger to the 

 machinery and motion of the clock. Instead of a disk, Dr. Locke 

 uses a wheel with sixty teeth, each of which when horizontal 

 strikes against the handle of a platinum tilt hammer, weighing 

 about two grains, and knocks up the hammer, which instantly 

 falls to a state of rest on a bed of platinum. The fulcrum of the 

 tilt hammer and the platinum bed rest severally on a small block 

 of wood. Each is connected with a pole of the galvanic circuit, 

 and the circuit is alternately broken and made by the rising and 

 falling of the hammer. The latter operation takes about one- 

 tenth of a second of time. 



I think it is manifest that either method will succeed in prac- 

 tice, which alone can test their relative excellence. To Mr. 

 Wheatstone, however, belongs the merit of priority in effecting 

 the primary object of causing the astronomical clock to make 

 and break the circuit of a galvanic battery, without injury to the 

 machinery or movement of the clock. 



Wai 



two 



inventions, and leaving it as a subject for special experiments, I 

 come now to the second requisite for the fulfillment of your 

 wishes, viz : the connexion of the astronomical clock with Morse's 

 electro-magnetic telegraph. In this department, so far as lam 

 informed, the first experiment has been made in this country. 



An experiment of the combination of an electro-magnetic clock 

 and Morse's telegraph register, was made by Professor Mitchell 

 and myself at the Cincinnati observatory on the 26th of October 

 last, on a plan, however, which I did not consider to be suitable 

 for nice astronomical observations. 



On the 17th of November last, Dr. Locke's delicate astronom- 

 ical clock, of his own construction, was supplied with the requi- 

 site apparatus made from his drawings by his son. At the ex- 

 pense of the coast survey, I directed wires to be put up for the 

 purpose of connecting his clock with the Cincinnati and Pitts- 

 burg line, about four hundred miles in length. The experiment 

 was eminently successful, and the registering of the seconds o( 

 time on the running fillet of paper was continued for two hours 

 at all the offices along the line, much to the astonishment of the 

 operators. I send you a specimen of the graduated fillet of paper. 

 It consists as you will notice, of an indented line of about nine- 

 tenths of an inch in length, followed by a complementary blank 

 space of about one-tenth. The two make a second of time, 

 commencing with the beginning of the line. 



This graduated fillet of paper I will call for the present the 

 automatic clock register* whether it is furnished bv Wheatstone's 



