. Farm implements, and the principles of their construction and use; an elementary and familiar treatise on mechanics, and on natural philosophy generally, as applied to the ordinary practices of agriculture ... SECTION II. EXPANSION BY HEAT. An important effect of heat is the expansion of bod-ies. Among many ways to show it, an iron rod maybe so fitted that it will just enter a hole made for the EXPANSION BY HEAT. 239 purpose in a piece of sheet-iron. If the rod be now-heated in the fire, it expands and becomes larger, andcan not be thrust into the hole. The expansion may-be more visibly show
. Farm implements, and the principles of their construction and use; an elementary and familiar treatise on mechanics, and on natural philosophy generally, as applied to the ordinary practices of agriculture ... SECTION II. EXPANSION BY HEAT. An important effect of heat is the expansion of bod-ies. Among many ways to show it, an iron rod maybe so fitted that it will just enter a hole made for the EXPANSION BY HEAT. 239 purpose in a piece of sheet-iron. If the rod be now-heated in the fire, it expands and becomes larger, andcan not be thrust into the hole. The expansion may-be more visibly shown and accurately measured bymeans of an instrument called the Pyrometer (). The rod a b, secured to its place by a screw at Fig. a, presses against the lever c, and this against the lever,or index, d, both of which multiply the motion, andrender the expansion very obvious to the eye when therod is heated by the lamps. If the rod should expandone fiftieth of an inch, and each lever multiplies twen-ty times, then the index (or second lever) will movealong the scale eight inches; for 20 times 20 are 400,and 400 50ths of an inch are 8 inches. Many cases showing the expansion of heated bodiesoccur in ordinary practice. One is afforded by themanner in which the parts of carriage wheels are boundtogether. The tire is made a little smaller than thewooden part of the wheel; it is then heated till, by 240 HEAT. expanding, it becomes large enough to be put on, whenit is suddenly cooled with water, and by its powerfulcontraction binds every part of the wheel together withgreat force. Hogsheads are firmly hooped with ironbands in the same way, with more force than could beever given by driving on with blows of the mallet. T
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Keywords: ., bookcentury1800, bookdecade1850, bookpublishernewyo, bookyear1854
