Prof. A. M. Mayer's Researches in Acoustics. 501 



old silver watch, beating four times to the second, by causing 

 this watch to gain about thirty seconds an hour on the clock, 

 so that at every two minutes the ticks of the watch and clock 

 exactly coincided. When the watch was held near the ear, 

 every one of its ticks was heard distinctly ; but on gradually 

 removing it from the ear the ticks of the watch became fainter 

 and fainter at the coincidences, and when the watch had been 

 removed to a distance of nine inches from the ear the ticks of 

 the watch were utterly obliterated during three whole seconds 

 of its ticks about the time of coincidence. On removing the 

 watch to a distance of twenty-four inches I found that I lost 

 its ticks during nine seconds about the time of coincidence. 

 It is here important to remark that the ticks of the clock are 

 longer in duration, as well as lower in pitch, than those of the 

 watch. With the watch remaining at a distance of twenty- 

 four inches from the ear, I listened with all my attention as 

 tick by tick the watch approached the time of coincidence. 

 Since the ticks of the watch are shorter in duration than those 

 of the clock, they are overlapped by the others about the time 

 of coincidence. Hence as, so to speak, the short ticks of the 

 watch glided tick after tick under the long ticks of the clock, 

 I perceived that more and more of the duration of each suc- 

 cessive watch-tick became extinguished by the tick of the 

 clock, until only the tail end of the short tick of the watch 

 was left audible ; and at last even this also crept under the 

 long tick of the clock, and the whole of the ticks of the watch 

 were rendered inaudible for nine seconds, at the end of which 

 time the front or head of the watch-tick, as we may call it, 

 protruded beyond the clock-tick, and then slowly grew up 

 into a complete watch-tick as before. In this succession of 

 events the tick of the old silver watch (made by Tobias) dis- 

 appears with a sharp chirp like a cricket's, and reappears with 

 a sound like that made by a boy's marble falling upon others 

 in his pocket. By this experiment, therefore, a gradual 

 analysis is made of the effect of the tick of the clock on the 

 tick of the watch, affording a beautiful illustration of the 

 fact that one sonorous sensation may overcome and obliterate 

 another. 



Experiments to determine the relative Intensity of the Clock- 

 ticks which obliterate the Watch-ticks. — The clock was placed 

 on a post in the middle of an open level field in the country 

 on nights when the air was calm and noiseless. The ticks of 

 the clock became just inaudible when my ear was removed to 

 a distance of 350 feet. The ticks of the watch became just 

 inaudible at a distance of twenty feet. The ratio of the squares 

 of these numbers makes the ticks of the clock about 300 times 



