249 



physiologist, Professor Rudolph Wagner, I consider it due to the 

 Royal Society and to myself to call to the Society's remembrance the 

 fact, that, in the memoir above referred to as having been laid before 

 them in 1835, the spot in question is not only pointed out and par- 

 ticularly delineated, but its physiological importance hinted at. 



The laying of a paper before a Society is an act of publication. 

 With the communication of my paper to the Royal Society in 1835, 

 the publication of Professor Wagner's paper in Miiller's Archiv was 

 contemporaneous merely. 



It is true, that though Professor Wagner's observations were only 

 first published in Miiller's Archiv for 1835, there is a note by the 

 editor, saying that the paper was received by him in 1834 ; but it is 

 also true, — and of this, were it necessary, proof could be easily ad- 

 duced, — that my paper was written also in 1834. 



In conclusion, I beg to apologize to the Royal Society for ob- 

 truding on their notice what may appear matter rather of personal 

 than general interest. 



3. — Description of the Electro-magnetic Clock. By C. Wheat- 

 stone, Esq., F.R.S. 



The object of the apparatus forming the subject of this commu- 

 nication, is stated by the author to be that of enabling a single clock 

 to indicate exactly the same time in as many different places, distant 

 from each other, as may be required. Thus, in an astronomical 

 observatory, every room may be furnished with an instrument, sim- 

 ple in its construction, and therefore little liable to derangement, and 

 of trifling cost, which shall indicate the time, and beat dead seconds 

 audibly, with the same precision as the standard astronomical clock 

 with which it is connected ; thus obviating the necessity of having 

 several clocks, and diminishing the trouble of winding up and regu- 

 lating them separately. In like manner, in public offices and large 

 establishments, one good clock will serve the purpose of indicating 

 the precise time in every part of the building where it may be re- 

 quired, and an accuracy ensured which it would be difficult to obtain 

 by independent clocks, even putting the difference of cost out of 

 consideration. Other cases in which the invention might be ad- 

 vantageously employed were also mentioned. In the electro-mag- 

 netic clock, which was exhibited in action in the Apartments of the 

 Society, all the parts employed in a clock for maintaining and regu- 

 lating the power are entirely dispensed with. It consists simply of 

 a face with its second, minute and hour hands, and of a train of 

 wheels which communicate motion from the arbor of the second's 

 hand to that of the hour hand, in the same manner as in an ordinary 

 clock train ; a small electro-magnet is caused to act upon a pecu- 

 liarly constructed wheel (scarcely capable of being described without 

 a figure) placed on the second's arbor, in such manner that whenever 

 the temporary magnetism is either produced or destroyed, the wheel, 

 and consequently the second's hand, advances a sixtieth part of its 

 revolution. It is obvious, then, that if an electric current can be al- 

 ternately established and arrested, each resumption and cessation 



B 2 



