JOHN MONTGOMERY BATCHELDER. 309 



vented a vulcanite insulator for stringing telegraph wires on poles or 

 other supports. This insulator was used on the telegraph between 

 Boston and Portland in 1853, and between San Francisco and Sacra- 

 mento in 1854. His electro-magnetic watch -clock is now m use in 

 various places, — notably in safety deposit vaults. The Batchelder 

 dynamometer for the measurement of power was one of the eai'liest 

 forms of practical dynamometers, and was of very ingenious construc- 

 tion. It was well adapted for the measurement of the power con- 

 sumed in various forms of mill machinery Among Mr. Batchelder's 

 other inventions are the following : — 



Vulcanite plate electric machine. 



Pressure sounding machine. 



Tide gauge hydrometer. 



Cards for the blind. 



Card catalogues for libraries. 



Porcelain and iron insulator. 



Instrument for drawing curves. 



Railway station and starting signal. 



Iridium surface copper plates. The first plate of large size, 21 X 16 

 inches, was exposed twenty-seven years without wax or other prepa- 

 ration, and was found still brilliant and unmjured. 



Hygrometer for regulating moisture in closed apartments and in 

 greenhouses. 



Oat basket for horses. To keep the feed at a uniform level, to pre- 

 vent waste, and to allow the horse to breathe freely. 



One cannot read the above list without being impressed by the re- 

 markable activity of Mr. Batchelder's mind. His note-books teem 

 with suggestions, and even in his eightieth year he made memoranda 

 and sufrgestions for future work. The writer of this notice remembers 

 to have received at the same time two letters : one from Mr. Batch- 

 elder, then in his eightieth year, in which he asks if it is possible to 

 make a magnet six feet long ; and another from Moses G. Farmer, 

 who had been many years stricken with paralysis, and had to be 

 wheeled about in a chair, in which keen interest was expressed in 

 regard to the oscillatory nature of electrical discharges. Thus two life- 

 lonT friends rose superior to the ills of old age, and manifested a calm 

 cheerfulness and scientific philosophy of life. No one could meet 

 Mr. Batchelder in the closing years of his busy life without gaining a 

 conviction that there was something undying in the spirit that could 

 so cheerfully meet the growing infirmities of age. When his last ill- 

 ness was unmistakably upon him, he took the writer into the cellar, — 



