of Edinburgh, Session 1881-82, 
799 
ance the theory is receiving from scientific men, particularly from 
those specialists whose domains in science it touches most nearly, 
it is already taking the place so long' held by the ingenious and 
fascinating theory of Mr. Darwin. 
The following Communications were read : — 
1. On Mirage. Part III. By Professor Tait. 
2. On a Red Resin from Dracaena Cinnabarri (Balf. fil.) 
Socotra. By J. J. Dobbie, Assistant to the Professor of 
Chemistry, University of Glasgow; and G. G. Hender- 
son, B.Sc. Communicated by Dr. Bayley Balfour. 
3. On Voice-Effort and Rhythm. By the Rev. J. L. Blake. 
Communicated by Professor Crum Brown. 
(Abstract.) 
In this paper the author enunciates and illustrates the following- 
propositions: — Speech is produced by distinctly separate jets of 
breath emitted under pressure; each such jet he names a mono- 
pressure. A monopressure may be used for the utterance of a 
single syllable, which may consist of a single vowel, or a vowel 
preceded or followed, or both, by consonants. In a monopressure 
the sound is weaker at the beginning and end, and stronger in 
the middle. The weak beginning, or the weak ending, of a mono- 
pressure, or both, may be used for the utterance of an unaccented 
syllable. There are thus four forms of a monopressure : — mono- 
syllabic ; dissyllabic, with the accent on the first ; dissyllabic 
with the accent on the second ; trissyllabic, with the accent on the 
second. These the author marks thus I, L, J, and JL. A large 
number of examples is given. The following will indicate the 
I L J ± 
use of the marks, — act, acting, react, reacting. The syllables 
(when there are more than one) of a monopressure need 
not, of course, all belong to one word ; and many words 
require more than one monopressure for their utterance. Thus 
words of three syllables require two monopressures, unless the 
