54 On a new Form of Monochord. 
material and of the same length, the number of oscillations 
is proportional to the square root of the tension, a thread of 
the same silk used in the last experiment and 1 metre long 
was subjected to various tensiuns. The tension to begin with 
was 9 er., obtained by weighting a small pill-box with shot, 
and the higher tensions were obtained by adding weights. In 
Table III., P denotes the load, N the number of oscillations for 
the fundamental note ; the second and third columns show 
SPL ONe 
that Se 
—/ Pi N, 
TABLE III. 
Pp Rey VP, Nn 
Speen = 3 ms oa 
or er. 
3 17-2 3 49 7 40°8 7-04 
16 4+ 93-4 4-08 64 8 46:2 8:02 
25 5 29:4 5-12 Sl 9 51-1 8:97 
36 6 34:1 5:98 
In order to show that the vibration-numbers of threads of 
equal length and tension vary inversely as their masses, it is 
best to employ thin metallic wires, since they are heavier than 
threads, and consequently a small error in the weights is not 
so perceptible. The weights, py, of wires employed for the fol- 
lowing experiments were determined by weighing four metres 
of each wire ; after being weighed a length of 1:20 metre was 
cut off and stretched between the siren and the pulley-wheel, 
so that the length of the vibrating portion was 1 metre; the 
tension (200 gr.) was chosen so great that the portion of the 
wire depending from the pulley-wheel did not need to be 
taken into account. 
TABLE LV. 
: D N 
Material. : Py de oh N. ae 
e p uf. ie Nv 
er. 
German-silver ... 0-660 i 90:5 1 
MSTAGSics oo. aoe ee 1604 0641 BY (a 0-63 
Prone ace to ke 9912 0:545 50°6 0:56 
After this description of the demonstration of Mersenne’s 
laws by means of this apparatus, it will not be necessary to 
