178 PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 



Locke was by nature a physicist and his reputation rests mostly 

 on his contributions to physical science. 



He was a pioneer student of electricity and magnetism, his 

 observations of terrestrial magnetism being especially important. 

 He designed and constructed new and original forms of appa- 

 ratus for physical research and it was probably this phase of 

 his work that was of greatest value to science. Among other 

 devices, special mention should be made of the very ingenious 

 and useful hand-level, generally known as Locke's level, of in- 

 estimable value in geological reconnoissance and in the explora- 

 tion of a mountainous or hilly country. He is credited with the 

 invention of a gravity escapement for clocks of the highest pre- 

 cision which has never been surpassed in excellence, and to him 

 unquestionably belongs the design and invention of the Electric 

 Chronograph. This he brought out about 1848 and for the first 

 completed model the United States government paid him ten 

 thousand dollars. What the microscope is for space and the 

 balance for mass measurement, the Electric Chronograph is for 

 time and its use is now almost co-extensive with that of the 

 balance. Locke died in 1856. During his life he made many 

 valuable contributions to scientific journals, had published many 

 volumes and was a member of numerous learned societies in this 

 country and in Europe. 



The story of the life'of Ormsby ]\L Mitchell, Locke's con- 

 temporary, associate, and sometimes bitter rival, is full of interest 

 and incident. Born in Kentucky in 1810, of \*irginia stock, at 

 the age of four years he was brought by his parents to Lebanon, 

 Ohio. At the age of fifteen with his knapsack on his back, as 

 became a nascent soldier, he started for the military Academy 

 at West Point, travelling a good part of the way on foot and 

 reaching his destination, the youngest member of his class (which 

 included Robert E. Lee and Joseph E. Johnston) as well as, no 

 doubt, the poorest, for he had but twenty-five cents left in his 

 purse. 



After a few years service in the Army he resigned, set- 

 tled in Cincinnati; studied law and was admitted to the bar. 

 His fondness for exact science soon drew him away from the 



