. The book of the farm : detailing the labors of the farmer, steward, plowman, hedger, cattle-man, shepherd, field-worker, and dairymaid. Agriculture. 390 THE BOOK OF THE FARM WINTER. that lies in iIk- liin-ctiou of the Htraia. or what in the language of agricaltural mechanics is called the breadth of tl>e 8witi»;-trcc. To apply the abore expression to practiceâsuppose a swing tree Fig. THE FOR TWO HORSES. of 3 feet in length between the points of attachment for the draoght, that its breadth is IJ inches and depth 3 inches, and another of the same breadth and depth, but
. The book of the farm : detailing the labors of the farmer, steward, plowman, hedger, cattle-man, shepherd, field-worker, and dairymaid. Agriculture. 390 THE BOOK OF THE FARM WINTER. that lies in iIk- liin-ctiou of the Htraia. or what in the language of agricaltural mechanics is called the breadth of tl>e 8witi»;-trcc. To apply the abore expression to practiceâsuppose a swing tree Fig. THE FOR TWO HORSES. of 3 feet in length between the points of attachment for the draoght, that its breadth is IJ inches and depth 3 inches, and another of the same breadth and depth, but whose length is 6 feet, then 1*5 X 3 X 3 1*5 V 3 V 3 in the case of the first we have ; =: 4*5: and in the second we have :=2*25 3 feet 6 â^the strength of these two being as 2 to 1; and. to make the 6 feet swing tree of equal strength with the othor, the breadth must be increased directly as the lengthâthat is to say, doubledâor the depth increased, so that its aqnore shall be double that of the former. Hence a swing-tree of 6 feet long, and having a breadth of IJ inches and depth 4j inches, will be equal in strength to the 3 feet sw-ing-tree with a breadth of IJ and depth of 3 inches: but, the depth remaining equal, the breadth is required to be doubled, or made 3 inches for the 6 feet swini; tree. (904.) To find the absolute strength of a bar or beam, sitoate as above described, we have tliis rule : Multiply the breadth in inches by the square of the depth in inches, divide the product by the length in feet, and multiply the quotient by the constant 660 if for oak, or by 740 if for ashâ the product will be the force in pounds that would break the swinetree or the beam.* Here, then, taking the former dimensions as of a small swing-tree. l-S X 3' X 740 = 3,333 lbs. the ab- solnte force that would break the tree ; but, taking into account the defect that all woods are lia- ble to break from crossing the fibres and other contingent defects, we may allow \ to eo for secu-
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectagriculture, bookyear
