cclxi 



The heat-alarm is an instrument which, by ringing a bell, indicates any 

 rise in the temperature of the surrounding atmosphere. The instrument 

 can be adjusted, if desired, so as to ring the bell on the approach of a man, 

 the radiant heat of the human body being sufficient to affect the instru- 

 ment at a distance of two feet. The heat of a spirit lamp will set it ringing 

 from a distance of two feet. The instrument can be most delicately set in 

 basements and places where an even temperature is maintained. It can be 

 set for any temperature, and has been successfully introduced into hotels. 



The principle of the heat-alarm depends upon the unequal expansion of 

 brass and steel. Two strips of these metals, four inches long, are soldered 

 together along their entire length. One end being fastened to a firm sup- 

 port, the warping of the bar on being heated or cooled is made to close a 

 circuit and ring a bell. Of course, it may be used as a cold-air indicator. 



Mr. Nipher asserted that these instruments had been brought to such 

 p>erfection, that any building which was worth protecting might easily be 

 so protected that it need not burn. If the heat-alarm is delicately adjusted 

 in a place where the temperature varies greatly, it w^ill occasionally give 

 an alarm when there is no fire. This is, however, a necessary failing in 

 all fire-alarms, and need not occur often. The city fire department is also 

 troubled in this way. Where the instruments are put in solely to bring 

 down the rates of insurance, it may often happen that this will be the only 

 good secured, for they are readily adjusted so that they will neither give 

 false alarms nor real ones. The contacts in the instrument are all of pla- 

 tinum, and its simplicity of construction in only equalled by its delicacy. 



Dr. Seyffarth sends the Academy five photographs of the sar- 

 cophagus which, thirty years ago, he purchased in Trieste for the 

 Academical Museum at Leipzig. The sarcophagus is of cedar 

 wood, and has preserved its specific odor during a period of 3400 

 years. It contains nearly 3000 figures, cut in demi-relief with 

 great skill. The photographs are said to represent every line of 

 the original. 



Silas Bent presented the Academy with twenty-two exceed- 

 ingly fine specimens of Corundum from North Carolina. He 

 remarked that this is the only locality where Corundum is found 

 " in place." 



Chas. K. Ramsay was elected to associate membership. 



May 7, 1877. 



Dr. Geo. Engelmann in the chair. 



Sixteen members present. 



Dr. G. I. Engelmann, chairman of Committee to confer with 



