Mechanical exercises, or, The elements and practice of carpentry, joinery, bricklaying, masonry, slating, plastering, painting, smithing, and turning . to slide in theboard KLMN, each two points O and K^ L andP, M and Q, N and R coinciding at this moment:KLMN will therefore represent a wide groovein the board; as this groove may be of anywidth, we may conceive the breadth to be verysmall or nothing, and may therefore be represent-ed by a groove or by the line AB parallel to KNand LM, and in the middle of the distance be-tween them. Instead of supposing the point Dalways moving to and fro in th
Mechanical exercises, or, The elements and practice of carpentry, joinery, bricklaying, masonry, slating, plastering, painting, smithing, and turning . to slide in theboard KLMN, each two points O and K^ L andP, M and Q, N and R coinciding at this moment:KLMN will therefore represent a wide groovein the board; as this groove may be of anywidth, we may conceive the breadth to be verysmall or nothing, and may therefore be represent-ed by a groove or by the line AB parallel to KNand LM, and in the middle of the distance be-tween them. Instead of supposing the point Dalways moving to and fro in the line EF^ wemay suppose a circle, or the end of a large cylin-dric pin moving in a very wide groove TUVWacross the slider OPQR. Now therefore all thedifferences between these diagrams and those inthe former plate, are only wide grooves in placeof lines passing longitudinally through the mid-dle : for the line AB is always conceived to movereciprocally from the one side to the other of theboard KLMN: now it is the same thing whetherone straight line slide longitudinally upon an-other fixed line, or whether a bar of any breadth move ^:^^^u -Flat^.
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Keywords: ., bookcentury1800, books, booksubjectcarpentry, booksubjectgeometry
