290 Mr. K. IT. M. Bosanquet on the Present 



when the disk is suspended as a torsion-balance, and its deflec- 

 tion observed, as the currents will not be formed except when 

 the disk is moving. 



The effect on the disk might be much increased by placing 

 four other electromagnets above the disk, each opposite one of 

 the lower magnets, as connected with it, so that the lower pole 

 of the upper magnet should be of the opposite name to the 

 upper pole of the lower magnet. In fig. 6 one pair of mag- 

 nets is shown with the opposite pair, and the wires connecting 

 them. The disk is seen in section, balanced on a needle-point, 

 between the two -pairs of magnets. The other four magnets 

 are not shown in the figure. 



XXXY. On the Present State of Experimental Acoustics, with 

 Suggestions for the Arrangement of an Acoustic Laboratory , 

 and a Sketch of Research. By R. H. M. Bosanquet, St. 

 Johns College, Cambridge. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



THE following paper presents an outline of suggested ar- 

 rangements and work for an acoustic laboratory, which 

 I hope shortly to be able to carry out. I have thought that 

 it may be of interest to the readers of the Philosophical 

 Magazine. Yours truly, 



R. H. M. Bosanquet. 



Experimental acoustics are at present in a condition which 

 is perhaps not entirely satisfactory. In the teaching of the 

 subject there is occasionally more demand upon the faith of 

 the learner than is altogether desirable in an experimental 

 science. I think that this arises from the difficulty of access 

 to those experiments which deal with the foundations of the 

 science. The prices charged for complete sets of acoustic ap- 

 paratus are enough to show that the possession of such appa- 

 ratus must be confined to few. Adequate sets of such apparatus, 

 used in a sufficient and convincing manner, are exceedingly 

 rare. Under these circumstances, that full experimental 

 knowledge which is desirable in a science of this description 

 does not generally exist. 



The ordinary apparatus and arrangements for demonstration 

 appear to err in some points. The effects are not produced in 

 a continuous manner, but by fits and starts, generally by 

 bowing on the sounding body. We do not analyze with ease 



