Author Description

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1864 Excerpt:...by hand, and then let it be thrown into gear, and regulate the working by the throttle and communication-valves; the object being to give the engine the same number of revolutions without the paddles as it usually has with them; taking care to have the condenser of the same temperature as in the ordinary working state of the engine. The Indicator having been previously fixed and adjusted, let a diagram be taken: it will be widely different from that when the load is on. Both the steam-line and vacuum-line will be much below the atmospheric line. The diagram may then be taken off, and divided as in the former case. Let the result of this diagram be worked off in the same manner as the common diagram, and the amount is the work the steam has performed, or in other words, the friction of the unloaded engine. This has been accomplished in the subjoined diagram. We would strongly advise the insertion of the bulb of a thermometer in the condenser of every engine, in addition to the barometer-gauge. The bulb must be entirely within the condenser, and the scale (at least that part of it which is above 50 or 60O) outside, in the engine-room. The thermometer chosen for the purpose must be graduated higher than the temperature of the steam in the boiler, otherwise it will burst when the engine is blown through. It must be placed on some part acted on freely by the steam, but free from the splash of the injection-water. When the engine is free from air it will then serve as a most delicate test of the vacuum. The temperature preserved should be about 100. This is what is commonly subtracted from the gross result obtained under ordinary circumstances, and denominated friction; but it is manifest that it is much less than the actual friction of the engine when turning th...