1891. | SCIENTIFIC AND BUSINESS PROCEEDINGS. 151 
Number three is a fragment of a well formed knife, while number 
four is the ordinary form of the Aztec knife made from the itztli. 
From the fact that it was found at the base of the altar, we may infer 
that it played some part in the human sacrifices. 
These fragments are all made from obsidian, and the cut rep- 
resents them in their exact size. 
Number one has attracted considerable attention among Mexican 
archeologists, and is important as corroborating the account of the 
human sacrifices. In digging at the base of the temple, I found a 
trowel shaped stone, (Fig. 5,) which might have been used in the mason 
work of either building orin repairing the temple. A piece which is 
almost the exact counterpart of this stone is in a large private collection 
in Mexico, and, before my finding this, was thought to be a unique 
example of an Aztec mason’s trowel. 
FEBRUARY 23, 1891. 
STATED MEETING. 
The President, Prof. H. L. FAircHILD, in the chair. 
Thirty-five persons present. 
The additions to the library were announced. 
Mr. J. E. Putnam spoke of the peculiar sensation produced by 
electricity. He had recently received a severe shock, which had 
rendered him quite unconscious for a few seconds. The current was 
received through a hand and bare arm, the strength of the current 
being about two hundred and forty volts. The sensation experienced 
was like a flash of lightning passing before the eyes. The effect was 
over in the fraction of a minute. 
The Secretary, Mr. Frank C. BAKER, gave an illustrated lecture on 
EXPLORATIONS IN YUCATAN AND SOUTHERN MEXICO. 
( Abstract.) 
The lecturer briefly outlined the course of the scientific expedi- 
tion sent out by the Academy of Natural Sciences of Philadelphia, 
under the charge ot Prof. Angelo Heilprin. The expedition left New 
York City Feb. 15, 1890, and returned June 10, 18go, having traversed 
