318 



Mercurial Thermometer, 10 of the Mercurial Thermometer 

 correspond to 9 of my dial. I have, therefore, no depend- 

 ence on the mercurial instrument I have, especially as no ten 

 degrees of the two instruments will agree, except the 10 on 

 which a correction is made, although they agree over a long 

 range at extremities. 



In presenting this account of my apparatus, I desire that a 

 knowledge of it may be made widely public, for the benefit of 

 those scientific men who may appreciate it, and desire to use 

 a similar apparatus constructed under their own supervision. 

 The details of all the parts are susceptible of numerous modi- 

 fications. I have not so much devoted my attention to the 

 test arrangement of all the parts, but have confined my efforts 

 more particularly to perfecting the Thermometer in that form 

 which will make it most reliable and least susceptible of im- 

 provement. The rods are on the outside of the case which 

 incloses the dial, registering apparatus, and clock. The ap- 

 paratus is very sensitive. The rods move the index freely to 

 \ degree, and the ticking of the clock attached imparts just 

 enough vibration to overcome resistance to a very minute 

 fraction of a degree. Indeed, on watching the index while a 

 slight change of temperature occurs, the index may be seen 

 to advance or recede with the tickings of the clock, almost 

 creating the impression that they are only parts of one move- 

 ment. 



Yours, JAMES LEWIS. 



Pending nomination, No. 397 was read. 



Dr. Wm. Harris, from the committee appointed to procure 

 a portrait of Judge Kane, reported it finished and in the hall 

 of the Society, and presented the bill for painting, framing, 

 &c., which was ordered to be paid. 



And the Society adjourned. 



