Register. 207 



The galvanic circuit in his clock, is made and broken by the 

 use of a circular metallic disk put on to the arbor of the sec- 

 onds' hand. Alternate intervals of a second, or one sixtieth of 

 the circumference, are made of a non-conducting substance. 

 The disk is insulated and connected with one pole of a galvanic 

 battery. A delicate spring connected with the other pole presses 

 gently on this disk. Thus the circuit is made and broken at 

 alternate seconds. This mode enables the primitive clock to con- 

 trol the motion of any number of clocks in connection with it. 

 iivery time the circuit is broken or made, any receiving clock- 

 wheel with sixty teeth may be made to advance one second, and 



this wheel may in the usual way control the minute and hour 

 wheel. 



Mr. Steinheil's galvanic clock is described in Schumacher's 

 astronomical annual, for 1844. The particular machinery for 

 making and breaking the galvanic circuit does not appear to be 

 described ; the general object is similar to Mr. Wheatstone's. 



I find, as yet, no account of the actual application of these 

 electro-magnetic circuits and astronomical clocks to the purpose 

 of permanently registering the current of time on the running 

 fillet of paper, as used in Morse's electro-magnetic telegraph. It 

 is, however, this latter combination that we must employ in our 

 telegraph operations for longitude. The experience of its ad- 

 vantages for that purpose, induces me, also, to recommend it for 

 the general objects of practical astronomy, as far as relates to the 

 record of minute subdivisions of time, such, for instance, as the 

 determination of absolute or relative right ascensions of the heav- 

 enly bodies, or of the local time of their culmination. 



The process to be used is dependent on two distinct contriv- 

 ances. The first is to cause the most delicate astronomical clock 

 to make and break the galvanic circuit at uniform intervals, (say 

 °f a second of time,) by an apparatus that cannot possibly injure 

 lf s machinery or its rate of performance, when connected with 

 the current of the most powerful battery. That of Mr. Wheat- 

 stone, and I presume of Mr. Steinheil, accomplishes this purpose 



effectually. 



Professor Bond, without having seen any notice of Wheat- 

 stone's invention, had proposed to make the mechanical contact 

 and separation of the pallet and teeth of the escapement wheel, 

 the closing and breaking of the circuit. This method may be 

 re adily applied to insulated portions of these parts. It will cer- 

 tainly succeed in practice. It is, however, liable to the danger of 

 deflagration of the metallic surface of contact,, and perhaps to 

 that of modifying the arc of vibration, by electric or electro-mag- 



n etic repulsion. 



Dr. Locke of Cincinnati, to whom I mentioned your wishes 

 °ft the 25th nf rvtnhpr nnt having seen a description of Mr. 



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