157 
of Edinburgh, Session 1866-67. 
Keport of the Committee on Safety-Signals. Presented to the 
General Railroad Convention, held at New York, October 24, 
1866. 8 vo . — From the Committee. 
Monatsbericht der Koniglich Preussisclien Akademie der Wissen- 
schaften zu Berlin. December 1866. Berlin, 1867. 8vo. — 
From the Academy. 
Monday , 29 th April 1867. 
Sir DAVID BREWSTER, President, in the Chair. 
The following Communications were read : — - 
1. Description of a Double and Triple Holophote, and of a 
Method of Introducing the Electric and other Lights 
By Sir David Brewster, K.H., F.R.S. 
2. On the Effect of Reduction of Temperature on the 
Coagulation of the Blood. By John Davy, M.D., F.R.SS. 
Lond. and Edin. 
In an excellent little work recently published on elementary 
physiology,* its author, when treating of the blood and its coagula- 
tion, remarks that a low temperature retards its coagulation ; and 
that ‘ £ blood kept at the freezing-point of water will not coagulate 
at all.” He adds : “ Blood thus kept fluid will, however, coagu- 
late when its temperature is raised; and blood has been thus 
cooled and warmed till near coagulation for three successive times 
without losing its coagulability.” 
That the lowering the temperature of the blood retards its coagu- 
lation is now unquestionable ; but the statement that it does not 
coagulate at all at the freezing-point of water, is new to me. Not 
aware that it has been the subject of experimental inquiry, I 
thought it right to make some trials to endeavour to determine 
* Lessons on Elementary Physiology. By Thomas H. Huxley, LL.D., 
F.R.S. 1866 . 
