Proceedings of the Polytechxic Association. 1017 



times, and received damages which, for the most part, could not be 

 repaii-ed with the means at the disposal of the division. One ball 

 struck her a foot under water, and another two feet under w^ater, at 

 the junction of the plates, loosened both and stuck in the backing. 

 The "Piauhy," " Barroso," and "Rio Grande" engaged the bat- 

 teries, while the three before mentioned went up the river. The 

 "Barroso" was not hit ; the "Rio Grande" received two shots, and 

 the " Piauhy " ten. Tlie latter, toward the end of the engagement, 

 had her turret disabled bv a splinter, but the gun was brought to 

 bear by aid of the twin screws. The Times' whole description of 

 this engagement leads the reader to infer that iron elads cannot resist 

 batteries under close fire. However, in this case, the vessels accom- 

 plished the work marked out for tliem. We have no plan of the 

 construction of these iron clads, but we may here add a recent 

 remark made by an American admiral, that with iron clads properly 

 made, and enongh of them, he would agree to pass any number of 

 forts and land batteries, 



Mr. Emery said that an iron clad ship that^would be injured by a 

 sixty-eight pound shot must be a very poor one. The smashing 

 effect of our fifteen inch shells was greater with a slower velocity 

 than one from a small gun at greater speed. 



Dr. P. H. Yanderweyde remarked that he examined the iron clads 

 when they came from Fort Fisher, and they were simple indentations 

 in them. The effect could be compared with the blow of a small 

 and large hammer. The small shot confines its effect to the place 

 it strikes. A large shot gives out more force in proportion to its 

 area. 



Railway Apparatus for Receiving ajst) Delxvering Mails. 



Mr. Freeman R. Sibley, of Auburndale, Mass., exhibited a model 

 of his and L. C. Wade's new plan for receiving and delivering mail 

 bags on railway trains, and spoken substantially as follows: 



It has long been a desideratum that some means should be pro- 

 vided whereby mail bags, express matter, and the like could be 

 delivered to and from express trains without stopping, thereby 

 obviating the delay, exposure, and inconvenience incident to the 

 usual method. Several means of accomplishing this result have been 

 brought forward from time to time ; but hitherto have been subject 

 to inherent defects that have destroyed their usefulness and availa- 

 bility. The apparatus, however, represented iu the accompanying 



