234 J. Locke on the Electro-Chronograph. 



trology under what are called " disadvantageous circumstances," 

 viz. : without the usual aids of instruments, or of instrument 

 makers, I was under the necessity of devising and making my 

 own apparatus. Under these circumstances, I had accumulated, 

 in the shop room contiguous to my laboratory, a very efficient 

 and perfect set of tools, among which are the lathe and other 

 shop tools made by the distinguished sculptor, Hiram Powers, 

 and used by him while he occupied himself as a mechanic at Cin- 

 cinnati. Whenever a new principle was announced; I found it 

 better to devise and make the apparatus suited to its illustration 

 than to purchase the stereotyped models often imperfectly planned 

 and worse manufactured. Thus avoiding all servile copying, and 

 venturing almost to avoid the trodden paths pointed out by books, 

 we drank our knowledge as much as possible from the fountain 

 itself, by appealing directly to nature. This course gave a fresh- 

 ness to popular instruction which evidently excited an interest 

 and produced an effect proportionate to the intense toil which its 

 prosecution demanded. 



During the winter of 1844-45, I had three assistants, viz. : 

 Thomas K. Beecher, A.M., and my two sons, John Locke, Jr., 

 and Joseph M. Locke, all of whom were extremely expert at 

 acquiring mechanical skill, and all of whom became enthusiasti- 

 cally active in the execution of instruments, which were thus 

 invented, modelled, made, and used by our corps. The exalted 

 character of my audience, composed as it was of men of high 

 attainment, incited us to the utmost exertion, which was at the 

 same time in the highest degree agreeable and yet too severe to 

 be long continued.* 8 It was in this course of lectures, when on 

 the subject of magnetic or electric clocks, that I devised and 

 made two clock-electrotomes, " break-circuits," or electrical u in- 

 terruptors," which, so far as I know, were new. I used these to 

 show my audience how they might be applied to the several pur- 



pose 



pend 



tances. In one of these, the electrical circuit was interrupted by 

 a conducting pendulum swinging at its lower point, through a 

 little mercury cup ; in the other a wheel with pins or teeth tripped 

 a little tilt hammer and broke the circuit, not by friction, but by 

 direct separation of contact and restored it by the reverse motion. 

 I had read the general accounts of the magnetic clocks of Europe 



the f ririional 



t 



That ai 

 Medical Colic 

 an I professors 



institutions of learning, "with members of the profession of niedicim 

 + Bains for example. 



hence included six presiding Judges, the President and officers of th 

 je of Ohio, the Catholic bishop and priest* of Cincinnati; the officer* 



f St Xavirr's College, professors and officers of other colleges and 



