172 PROCEEDINGS OF THE AMERICAN ACADEMY 



and outside of the top, as it is in the musical pipe : the only difference 

 being, that in one case the air is driven by the mouth against the lip 

 of the embouchure, and in the other the lip of the top is made to 

 strike against the air. I have not been able to find any allusion to 

 the question whether the note which the top yields varies with the force 

 of the blast which the top itself gives by its own motion. But I have 

 succeeded myself in producing two of the harmonics, that is, one 

 besides the fundamental sound. Success in this experiment requires 

 that an extraordinary velocity should be given to the top, greater 

 than is possible except when the top is small. But if a small top is 

 started with great energy, it gives out at first a high sound. As the 

 velocity slackens, this sound dies out, and the top is silent for some 

 time. Afterwards, as the motion diminishes, another and lower sound 

 starts up, which is the one commonly heard in humming-tops, and the 

 only one possible to excite by the usual way of starting the top, if it is 

 large. This curious experiment may be worth recording, as carrying 

 one step further the analogy between the theories of the sounds of the 

 humming-top and of other wind instruments." 



Mr. Sherwin alluded to a phenomenon accompanying the 

 recent burning of a large building in Cambridge. Tlie ap- 

 pearance to him, at the distance of several miles, was that of 

 a tall column of light elevated about 20° above the horizon, 

 appearing at first like some extraordinary meteoric phenom- 

 enon. It might be accounted for, he thought, by a series of 

 reflections from clouds at different elevations, or perhaps more 

 probably by mirage. In 1811 he had seen a similar appear- 

 ance 24° high, which proved to have been caused by the burn- 

 ing of a paper-mill forty miles off". 



Professor Horsford exhibited specimens of Cochituate water, 

 together with the various products of his recent examination 

 and analysis of it. 



