Aue. IV.—The Micon f peteng invented by Joun Locke, 
tio M. D., Principal of Cincinnati Female Academy. igi 
TO THE EDITOR. 
Dear Sir—For several years I have been procuring a variety of 
miniature or pocket instruments for mathematical and philosophical 
purposes. To the pocket sextant, telescope, level, &c. I have been 
desirous to add a compass, which should have nearly the accuracy of 
a surveyor’s large compass of the best construction. 
Abe several fruitless attempts to procure one already made, I at- 
to invent one and have succeeded so much to my satisfaction 
att it has seemed to me that an account of my invention would not 
be useless or uninteresting to the public.* My compass has the grad- 
uated rim attached to the needle and revolving with it in the man- 
ner of the card of the mariner’s compass Fig. 1. This rim i 
et ee y experiments on this instrument in Feb. 1832. I ieee 
| Wells, peers for ate by avery ingenious young artisan of this city Bon T. 
iaeys iny direction by ry Cox, for Mr. boca. =] 
