319 



the case which incloses the dic'il, registering apparatus, and clock. 

 By a peculiar arrangement of the clock-work, the hammer move- 

 ments, and therefore the times of registration, may be adjusted to 

 quarter-hour, half-hour, or hour intervals, and may be changed 

 from one to the other at the will of the observer. 



As regards the performance of this very ingenious instrument, 

 Prof. Rogers had obtained many interesting facts from Dr. 

 Lewis, illustrating its great sensitiveness as compared with the 

 common mercurial thermometer, and showing the comparative 

 steadiness and accuracy of its registration within the small limits 

 of error due to the friction and thermal disturbances to which it 

 is exposed. The inventor, with laudable disinterestedness, asked 

 for a thorough scrutiny of the practical value of his contrivance. 

 While offering information to others, he was himself a severe 

 critic of its daily workings, and has been led* since its first con- 

 struction to introduce various modifications adapted to reduce 

 resistance, to exclude radiation, and otherwise to improve its 

 fidelity in appreciating and registering the changes of tempera- 

 ture. A somewhat longer experience may be needed to discover 

 all the peculiai'ities of action incident to the construction of the 

 instrument, and to give it the permanent reliability for minute 

 registration at which the inventor aims. 



Looking to the general principle of the instrument, and to the 

 improvements thus far made in it, and relying on the faithful 

 observation, as well as the ingenuity of Dr. Lewis, for giving it 

 all the accuracy and permanent reliability of which it is capable, 

 Prof. Rogers felt it his duty to commend the registering 

 thermometer of Dr. Lewis to the Society, as an instrument 

 worthy the critical examination of men of science, and one which 

 promised to become a valuable help in meteorological observation. 



Dr. A. A. Gould presented, in the name of Mr. 



Charles A. White, a paper entitled " Observations upon 



the Geology and Paleontology of Burlington, Iowa, and 



its Vicinity." It will be published in full in the Journal 

 of the Society. 



Prof. Rogers remarked on the importance of the 

 facts set forth in the paper of Mr. White, not merely as 



