The Penberthy Engineer & Fireman; A Monthly Magazine Published in the Interests of Steam Users Volume 22

The Penberthy Engineer & Fireman; A Monthly Magazine Published in the Interests of Steam Users Volume 22

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 edition. Excerpt: that the valves will not carry in starting up, but will be tripped by the governor at all speeds. On some makes of engine, this cam will require more movement than on others, while on a few engines, the cam and lever are cast integral, which prevents changing, but the position is found by calculation. In this case new levers must be secured from the makers; no changes were made in the governor. PERFECT VACUUM NOT YET But within a one hundred and thirty millionth of it. No perfect vacuum can be even approached by any pump. After the mechanical piston pumps came the mercury pump, but that took a very long time. Then the Gaede pump, and the Geryck pump improved matters somewhat, but were not satisfying to scientists, and now we have a new device, ingenious, swift and reliable. Suppose that we have a sealed tube containing air. If we place this in liquid hydrogen, the air in a few minutes becomes a solid in the bottom of the tube. If there were absolutely nothing but air in the tube, and if all the air were frozen we would have a perfect vacuum; but air contains what the chemist calls "traces" of several inert and hard-to-freeze gases, two of which are helium and neon. The tiny amount of these rare gases found in the air is of course left in the space, and so a perfect vacuum does not appear. But helium has been liquefied also. As liquefied helium is the coldest thing obtainable, it will not freeze any more of itself. To make the vacuum more complete, however, it was decided to put some charcoal into the tube. It had long been known that hot charcoal had the power to obsorb or "occlude" gases; but little was known about its power when as cold as liquid air. A great surprise was in store for the first man to try it, more

Product details

  • Paperback | 192 pages
  • 189 x 246 x 10mm | 354g
  • United States
  • English
  • black & white illustrations
  • 1236950852
  • 9781236950857