AMERICAN INSTITUTE. 605 



plirey Davy's lamp for safety in mines. The fluids are guard- 

 ed by wire gauze, both in the cans and the himps, so that 

 an explosion is not possible so long as these lamps are per- 

 fectly sound. Mr. Newell set fire to the lamp wicks and then 

 poured from the can the burning fluid into the burning lamp. A 

 small flame momentarily plays on the nose of the can. Newell's 

 wire gauze is made of copper wire properly electrotyped by silver 

 to prevent corrosion from the acid of the fluid. He exhibited the 

 can emptied of all the fluid except the very small portion adhe- 

 ring to its interior. A cork was put into the top of the can, a 

 small aperture made near the bottom, a flame touched to the hole, 

 and the admixture of air with the very small portion of fluid 

 caused an explosion as quick or quicker than gunpowder, driving 

 the cork out violently. 



A letter from Prof. Benjamin Silliman, sen., of Yale College, 

 was read, expressing entire confidence in this safety lamp. 



The Chairman called up tlie regular question " The best method 

 of conducting steam from the boiler to the piston." 



Mr. Fisher who had promised to prepare a paper on the subject 

 now read it, and illustrated by drawings on the black board, viz : 



" The subject now under discussion, the distribution of steam, 

 is one that was once but little understood before the necessities of 

 locomotives pressed it upon the attention of engineers, and, after 

 ten years' submission to the old rules, awakened them to think 

 for themselves, and to adopt their valve gear to the peculiar ser- 

 vice it had to perform. The first innovation was not, theoreti- 

 cally, calculated to stagger the ancient faith, and reconcile them 

 to new practice ; but practical trials, carefully observed, proved 

 that a gain was efiected, and thus opened their minds to a candid 

 review of the old and new theories. And in aid of this practical 

 evidence, they had the influence of an error into which tliey had 

 fallen, respecting the duty of locomotives, or the work done 

 by a given quantity of fuel, which, as they computed, did not 

 exceed six or seven million pounds lifted a foot high by eighty- 

 four pounds of fuel, which was but one-eighteenth of what 

 the best Cornish engines were reported to have done. 



" This error arose from an assumption that the resistance to 

 rolling was constant at all speeds, and amounted to eight pounds 

 per ton, including collisions, flange friction, and the sliding of 

 the wheels which occurs when they run upon unequal diame- 

 ters. But it is now well known that, at the speed of passenger 

 trains at that time, these resistances could not have been less 

 than eighteen pounds per ton, and probably were much more. So 



