378 PROCEEDINGS OF THE AMERICAN ACADEMY 



of the American frigates in the war of 1812, says that some of them 

 used shot weighted by a leaden core. This I believe is not true, but it 

 shows the opinion of this old engineer, of the advantage that might be 

 expected from increasing rather than diminishing the specific gravity 

 of cannon-shot. Yet Captain Rodman's hollow shot seems to be looked 

 to (pp. 289, 307) as the missile to meet iron-plated ships. Whether it 

 is intended to explode them against the ship, or to depend upon their 

 direct percussion, is not very clearly stated. The effect would proba- 

 bly be very much alike in both cases. Indeed, Captain Rodman 

 admits (p. 298), that, although " none of these broke in the gun, some 

 did break in the sand-bank after the sand had been packed hard by 

 repeated firing." God forbid, then, that we should ever have to try 

 them against the sides of the Gloire or the Warrior. 



I have thus examined some of the prominent points in the labors of 

 Captain Rodman, as they are detailed in his reports ; and, without, as I 

 hope, making any remark disrespectful to him as an ofiicer and gentle- 

 man, I have declared freely what seems to me the value of the most 

 important of the experiments and conclusions given in his work. Re- 

 peating here what I declared in an earlier part of this paper, that I 

 think well of his method of cooling the hollow casting which is to form 

 a gun, I think that there is good reason to believe that these guns will 

 be somewhat superior to those made in the usual method. In the prac- 

 tice of casting in this way, however, great care must be observed to 

 avoid the explosion which may occur should the cooling water find its 

 way from its conductor into the body of the mould. 



Five Ixuudred and fonrtb meeting. 



February 11, 1862. — Monthly Meeting. 



The President in the chair. 



The Corresponding Secretary read letters of acceptance from 

 the Right Rev. Bishop Fitzpatrick and Dr. John Dean, re- 

 cently elected Fellows, and from John M. Ordway, elected As- 

 sociate Fellow of the Academy. 



Professor Peirce, from the Committee to which the subject 

 was referred, made a report upon the work of Capt. Hum- 

 phreys and Lieut. Abbot, U. S. Topographical Engineers, 

 upon the Mississippi River and the best mode of protecting its 



