324 
MR. FARADAY ON THE FORMS AND STATES 
(75) removes a good deal of the difficulty experienced, and the production of 
slow, regular, sustained vibrations, more (67. 69). 
80. These elevations I will endeavour to distinguish henceforth by the term 
heaps. 
81. The crispation on the long plate of glass described (67) always ulti- 
mately assumed a rectangular arrangement, i. e. the heaps were equidistant, 
and in rows parallel or at right angles to each other. The rows usually form 
angles of 45° to the sides of the plate at the commencement ; but if the vibra- 
tion be continued, the whole system usually wheels round through 45° until 
the rows coincide with the edges of the plate. 
82. The lateral dimension of the heaps remained constant notwithstanding 
considerable variations in the force of vibration. But it was soon found that 
variation in the depth of water affected their number ; that with less water the 
heaps were smaller, and with more water larger, though the sound and there- 
fore the number of vibrations in a given period remained the same. The 
number of heaps could be reduced to eight or increased to eleven and a half 
in the three inches by a change in no other condition than the depth of fluid. 
83. With the above plate (67- 81) the appearances were usually in the fol- 
lowing order, the pool of water being quadrangular or nearly so, and the ex- 
citing rod resting in the middle of it. Ring-like linear heaps concentric to the 
exciting rod first form to the number of six or seven ; these may be retained by 
a moderated state of vibration, and produce intervals which measured across 
the diameter of the rings are to the number of ten in three inches, with a cer- 
tain constant depth of water. By increasing the force of vibration the altitude 
of these elevations increases, but not their lateral dimension, and then linear 
heaps form across these circles and the plate, and parallel to the bridges, 
having an evident relation to the manner in which the whole plate vibrates. 
These, which like all other of these phenomena are strongest at the part most 
strongly vibrating, soon break up the circles, and are themselves broken up, 
producing independent heaps, which at first are irregular and changeable, but 
soon become uniform and produce the quadrangular order ; first at angles of 
45° to the edges of the plate, but gradually moving round until parallel to 
them. So the arrangement continues, unless the force be so violent as to break 
