308 JOHN MONTGOMERY BATCH ELDER. 



like suggestions from you in relation to the proper mode of making 

 tliem. I suppose the depth should not be great, — say five to ten 

 feet. I propose to drive in the same cellar an iron tube, and allow 

 the thermometer to remain within a few inches of the bottom. The 

 temperature of the surface of the ground should also be recorded. . . . 

 The cost of the apparatus would be about twenty-five dollars, and I 

 should make no charge as observer." 



Mr. Batchelder was a contemporary of Agassiz, Wyman, Bond, 

 Gibbs, and Gould, and walked with the men who have contributed 

 so much to make Cambridge a university centre, and aided them often 

 by his practical science. No man ever had greater appreciation of 

 intellectual qualities than he had, and he was always on the lookout 

 for some mechanical paradox to present to his friend, Professor 

 Peirce, or some peculiar fact in natural history to be elucidated by 

 Agassiz or Wyman. Joined to this reverence for pure science was a 

 marked talent for invention. Before 1853 he invented independently 

 the Bunsen burner, which is so indispensable in all laboratories, and 

 which is used so extensively in the arts. His apparatus for deep-sea 

 soundings is still used in the United States Navy, and is highly ap- 

 proved by the British Admiralty. A short while before his death, 

 Mr. Batchelder received from an officer in the English Navy a highly 

 complimentary notice of the performance of his apparatus. His tide- 

 meter for soundings at a distance from the shore has been used by 

 the United States Coast Survey in various places. During the block- 

 ade in 1862-63 it was used in eight fathoms of water off Hilton 

 Head, and was instrumental in securing the safety of government 

 vessels. We find among his papers many memoranda in regard to 

 submarine signals, and when he was over seventy years of age he 

 actively carried out experiments on transmitting signals under water 

 by employing water as the medium of propagation of sound instead of 

 the air. By means of the sound of escaping steam he succeeded in 

 transmitting sound over a mile under water. His ultimate object was 

 to give mariners some method of ascertaining the proximity of ships in 

 a fog. The subject of electricity was always a fascinating one to him. 

 In connection with Moses G. Farmer he invented the compound tele- 

 graph wire, which consists of a steel core and a sheath of copper. 

 The steel wire was for strength, and the copper covering for electrical 

 conductivity. The inventors made many experiments to coat the steel 

 wire successfully with copper, and finally succeeded. Early realizing 

 the importance, not only of providing telegraphs with a strong wire of 

 good conductibility, but also with an insulator, Mr. Batchelder in- 



