Association of American Geologists and Kataralisls. 131 



The levers in Ferguson's pyrometer act like levers of the 

 third kind ; in Daniell's, like one of the first kind : but it is 

 difficult to decide, by mere inspection of the diagram that ac- 

 companies the description of the register pyrometer, whether 

 an error similar to that in Ferguson's arrangement, or in- 

 deed, whether any error exists in Daniell's scale. I have 

 not had an opportunity to inspect the instrument itself. 



All who have brought forward pyrometers endeavour to 

 connect them as supplements to the thermometer, which, it 

 i!j now generally admitted, is not really consistent with it- 

 self from its lower to its higher limits ; an approximation to 

 an accurate continuation of Fahrenheit's scale is therefore 

 all that can be expected. The difficulties that stand in the 

 way of a solution of the problem, seem to arise from the 

 small expansion of the metals employed, which thus requires 

 the intervention of levers and pinions, that may not " per- 

 form with theoretical accuracy ;" from unequal expansions 

 by equal increments of heat ; and in the method now sub- 

 mitted, from the increasing specific heat of metals. At pre- 

 sent, to me it seems possible to determine, within 100'' at 

 least, a temperature not greater than 1200°, or double that of 

 boiling oil, by means of the fusible alloy, and by a method 

 (perhaps unsuitable for a permanent instrument) in which 

 those suspected causes of error may be evaded. If opportu- 

 nity be afforded, and if the inquiry be attended with even mo- 

 derate success, I may, with permission, take leave to return 

 to this subject. 



Meeting of Association of American Geologists and Naturalists, 

 held at Boston, September 27, 1847- 



This Association met, according to adjournment, in the Marl- 

 borough C'liapcl, Tuesday morning, at 10 o'clock. 



The meeting was called to oi'der by Dr John C. Warren, of this 

 city, chairman, pro tempore. The proceedings of Monday were 

 then read by the secretary, Dr J. Wyman. Professor Silliman, of 

 tiie Standin"^ Committee, after making a few remarks relative to the 

 death of Dr Binney, nominated Professor WilHam B. Bogcrs as 

 permanent chairman of the present meeting, and ho was unani- 



