404 TRANSACTIONS OF SECTION A. 
The results of this investigation are chiefly interesting in showing that 
the specific heat of mercury passes through a minimum value at about 
140° C. and increases fairly rapidly up to the boiling-point. In this 
respect it resembles water very closely, which possesses a minimum point 
at 37° C., or at about the same relative position between the freezing and 
boiling points in the two cases. 
Specific Heat of Mercury at various Temperatures. Actual Observations. 
Electrical Method Water-cooled Method 
Specific heat Specific heat 
Temp. Pract Temp. cecrsdtell 
LPio8 Os 
2°93 0:033489 159-65 0:03287 
4-45 0:033460 160°46 0:03297 
18°37 0:033318 222°85 0:03291 
24:52 0:033261 224-46 0:03304 
31:68 — 0:033194 225-49 0:03299 
32°44 0:033185 252-73 0:03309 
36°59 0:033178 253°06 0:03309 
45:00 0:033085 261°57 0:03321 
53°39 0:033040 268'23 0:03318 
65:22 0:033007 
83°89 0:032931 
3. The Relation of Vocal Quality to Sound Waves. 
By T. Proctor Haun, M.A., Ph.D., M.D. 
An apparatus for making enlarged tracings of sound waves from a 
cylindrical graphophone record, the magnification ranging from 150 to 
2,500 times, was described. In the sound waves two elements are distin- 
guished, impulse and resonance, which are illustrated by waves from the 
cornet, violin, bugle, &c. Vocal waves are found in groups regularly 
repeated. Each group contains a single impulse frem the vocal cords, 
together with one or more sets of resonance waves produced by vibrations 
of the air in the vocal tubes. Pitch is determined by the number of 
impulses per second—i.e., by the number of wave groups—and is not 
affected by the character of the waves within the groups. The vowel quality 
of vocal sounds is not perceptibly affected by the number or form of the 
resonance waves, but is dependent upon their periodicity. The rate of 
the resonance waves may be calculated from the length of the air tubes 
upward from the vocal cords. The calculation shows, for example, that 
the sounds m, n, ng, all contain a resonance wave whose period is about 
530. The mean rates found from measurements of the enlarged waves are 
for m 550, for n 535, for ng 580. The observed rate for the sound of ‘a’ 
in the word ‘ great’ is 420, and for the sound of ‘a’ in ‘ mat’ 770 waves 
per second. The investigation is continued. 
4. Electric Splashes on Photographic Plates. 
By Aurrep W. Portsr, B.Sc. 
The author exhibited lantern slides of the figures obtained by develop- 
ing photographic plates over which electric discharges had been allowed 
to spread. These were in extension of a series shown to the Physical 
Society of London last November. Splashes with different gases surround- 
ing the plate prove, from their great dissimilarity in the case of ‘ negative’ 
