Rudimentary treatise on the erection of dwelling-houses : illustrated by a perspective view, plans, elevations, and sections of a pair of semi-detached villas with the specification, quantities, and estimates and every requisite detail, in sequence, for their construction and finishing / by . hich the pointed limbsmay be set perpendicular as usual. The extent oropening between the points is regulated by a screwpassing through a socket, f, and terminated at theother extremity by a milled head, by which the screwis turned round. Between this milled head and thenearest pointed limb is f
Rudimentary treatise on the erection of dwelling-houses : illustrated by a perspective view, plans, elevations, and sections of a pair of semi-detached villas with the specification, quantities, and estimates and every requisite detail, in sequence, for their construction and finishing / by . hich the pointed limbsmay be set perpendicular as usual. The extent oropening between the points is regulated by a screwpassing through a socket, f, and terminated at theother extremity by a milled head, by which the screwis turned round. Between this milled head and thenearest pointed limb is fixed what is called a micro-meter head, decimally divided round its outer orcylindrical edge. One turn of the screw carries themicrometer head completely round; therefore, whenpart of a turn only is given to the screw, the divisionson the head show what fraction of a turn has beengiven, and if it be known what number of turns orthreads of the screw are equal to one inch, the points of SrRING DIVIDERS. 79 these compasses may be thus set to any small definitemeasure of length with the utmost precision. Theindex or zero for reading the fraction of a turn of thescrew is marked on the point limb below b : thus thisinstrument may be considered as a beam compass ofsmall dimensions and minute Spring Dividers. This instrument, represented in the accompanyingdiagram, is particularly useful for repeating divisionsof a small but equal extent—a practice that has thename of stepping, for which a small pair of haircompasses would also be found useful when the head isconstructed as shown in the adjoining figure, or similarto that of the bow compass before described, and forreasons before stated. The upper part forming thehandle is composed of brass or silver, whilst the lowerpart from a towards the points is made of one piece ofsteel of a spring temper, whereby the two points are 80 ERECTION OF DWELLING-HOUSES. always endeavouring to recede from each other, or openby their elastic
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectarchitecturedomestic
