ON RAIL-ROADS. 295

surface of the inner pipe, would both destroythe noise and heat the water.

The noise from the working parts of theengine is comparatively trifling, and might bealmost entirely annihilated by a little care inthe construction.

There is another objection urged againstthese engines, certainly not on account of theirapplication to Rail-roads, but extending to allsimilar engines, viz. on account of the greatelasticity of the steam in the boiler. I neednot again repeat, that the elasticity is consider-ably less in the cylinder. At the first intro-duction of these engines it was found, asbefore stated, difficult to keep up a properdegree of elasticity of steam in the boiler; orrather, an adequate supply of steam ; and asthey had to travel on short stages, the pressurein the boiler was increased to 50 lbs. per squareinch, which, in the journey, was allowed toexpand, and thus acted as a sort of reservoir.Since they have been improved, a sufficientquantity of steam is capable of being raised atall times ; by enlarging tire apertures betweenthe boiler and the cylinder, the elasticity otthe boiler might be greatly reduced; and theengine might be then made to assume thecharacter of a low-pressure engine.