chairman's annual report. 163 



tened to it and who watched the illustrative experiments. 

 He presented an analysis of the various problems in- 

 volved in the subject as they had appeared under his 

 own careful observation, and in a wholesome way taxed 

 the powers of the society in their endeavor to follow his 

 original and exceedingly ingenious explanation of its 

 mysterious motions. He also, on another evening, 

 opened, in a very able and interesting manner, the ques- 

 tion of the " Uniformity of Climate in Past Geological 

 Ages,' 1 the discussion being subsequently continued at 

 considerable length by other members. 



Dr. W. G. Stevenson introduced to the Section a 

 couple of fine sharks, captured by himself and Mr. C. B. 

 Herrick, at Nantucket, Mass., and gave an elaborate 

 and accurate description of their characteristics and re- 

 lations to other species. This will be one of the most 

 valuable jjapers in our proceedings for the year. On 

 two other occasions, he also read a paper on ' l Our Local 

 Mammalian Fauna,' 1 and gave a "List of Birds found 

 in this Vicinity, and represented in the Museum," by 

 which he endeavored to increase the interest of the Sec- 

 tion in the complete collection and study of the ani- 

 mal forms of this vicinity. 



Prof. Maria Mitchell presented, in her usual clear and 

 attractive way, the subject of the planet Saturn, 

 bringing before the society, with the assistance of black- 

 board illustrations, the results of many careful original 

 observations. 



Prof. Cooley discussed, during one evening, with ad- 

 mirable clearness, "The Laws of the Compressibility of 

 Gases," describing the successive systems of experimen- 

 tation which have been devised to ascertain these laws 

 and the latest conclusions reached. He also exhibited a 

 new, simple, and perfectly effective apparatus, of his 

 own invention, which demonstrates these laws with 

 scientific accuracy, while by the lantern the results are 



115 



