90 PROCEEDINGS OF THE AMERICAN ACADEMY 



well, and Mr. Charles Jackson, Jr. made various inquiries ; but 

 the reason why some pipes were more acted upon than others 

 was not elicited. 



Dr. Gray exhibited specimens of a Spongilla taken from 

 the Cochituate water-pipes, in which, at some places, espe- 

 cially where there is no rapid flow, this production is said to 

 form with great rapidity. 



Three Imudred and. ninety-fifth meeting. 



February 28, 1854. — Semi-Monthly Meeting. 



The President in the chair. 



The Corresponding Secretary acted as Recording Secre- 

 tary, and read the record of the proceedings of the preceding 

 meeting. 



Professor Cooke submitted a memoir upon a subject which 

 he had brought before the Academy at a former meeting, 

 viz. " The Numerical Relation between the Atomic Weights, 

 with some Thoughts on the Classification of the Chemical 

 Elements." This was illustrated by a new classification of 

 the elements in natural groups. 



Dr. W. F. Channing stated that he had recently assisted in 

 measuring the electricity evolved by two large magneto-elec- 

 tric machines constructed in Providence. These consisted 

 essentially of armatures with inducing coils revolving before 

 magnets. The amount of electricity evolved by the smaller 

 machine was equal in quantity and intensity to that from a 

 series of fifteen Grove's cups in full action. The amount of 

 electricity evolved from the larger machine was equal to that 

 from one hundred and forty-four Grove's cups, arranged two 

 abreast in a series of seventy-two. The interesting fact here 

 is, that galvanic electricity may be obtained from the magneto- 

 electric machine for practical purposes, in greater quantity and 

 at less cost than from the galvanic battery. 



Professor Cooke communicated the fact, that an alloy of zinc, 

 with a small quantity of antimony, after having been acted 



