* 



J 



238 ./. Locke on the Electro-Chronograph. 



the circumstances of the invention. Mr. Walker, having witness- 

 ed the development of the thing here, and leaving on Nov. 19th, 

 travelled direct for Philadelphia, where the article appeared on 

 Dec. 1st. It is from an eye-witness, while it was fresh in his 

 mind, and will therefore be the more satisfactory. 



c Dr. John Locke, of Cincinnati, has invented a very cheap 

 and simple instrument, which can be attached to the same pivot 

 along with the second hand of any clock, and which will, when 

 put in connection with the telegraphic circuit, make the clock 

 beat at the same instant all along the line. 



" The hours, minutes and seconds, may be registered on the 



fillet of paper, and by striking on the telegraphic key at the in- 

 stant of any occurrence, the date of it is recorded- on the same 

 paper to the hundredth of a second. This invention will be use- 

 ful for many practical purposes* It makes the current of time 

 visible to the eye in a permanent record. It does not change the 

 rate of going of the most delicate clock. It will doubtless be ap- 

 plied hereafter to many purposes for the advancement of science; 

 such as the determination of geographical longitude, in connec- 

 tion with transit instruments, the measurement of the velocity 

 of sound ; perhaps, if the circuit be long enough, of the lightning 

 itself. 



11 The mechanical invention is due to Dr. Locke. It is proper 

 however, to remark, that the first suggestion of the use of the 

 telegraph line in connection with the determination of longitude, 

 was made by Prof. A. D. Bache, the Superintendent of the United 

 States Coast Survey, in the winter of 1843-4. 



"The subject has, under his direction, been making constant 

 progress towards the perfection of the art. Several thousand 

 dollars have been expended hi the construction of lenses, instru- 

 ments, &c., and in practical observations for longitude. The 

 great desideratum in the work was a telegraphic clock, which, 

 without having its performance injured, should register, as Dr. 

 Locke's attachment does, the hours, minutes and seconds at the 

 stations of the coast survey, in connection with the line. The 

 list of requisites* for coast survey operations derived from three 

 years experience, was furnished to Dr. Locke under the direction 

 of the Superintendent, by Sears C. Walker, the assistant in charge 

 of this department, on the 28th of October. The invention of 

 the attachment was completed by Dr. Locke, on the 4th of 

 November. A model was constructed by Dr. Locke's son, a skill- 

 ful mechanician, and on the 15th was attached to an astronomical 

 clock, made by Dr. L., with his own hands. The coast survey 



* 



* This list of requisites did not include any suggestion or hint with regard to the 

 u printing' or chronographs mode of observing. It consisted of the suggestions 

 specified on page 235, in italics. 







