Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 1, 1802).djvu/74

50&#93; S o] A N E half an inch in diameter, fastened into the pillar. Upon this axis turns a wooden tube ; at the top of which is placed a vane, of the same materials, twenty-one inches long, consisting of a quadrant, graduated, and shod with an iron ring, notched to each degree ; and a counterpoise of wood on the other, as represent- ed in the hgure. Through the centre of the quadrant runs an iron pin } upon which are fastened two small round pieces of wood, serving as moveable radii to describe the degrees upon the quadrant, and as handles to a velum or sail ; the pane of which is one foot square, made of canvas stretched on four battens, and painted. On the up- per batten, next to the shod rim of the quadrant, is a small spring, which catches at every notch, cor- responding to each degree, as the sail may be raised on die pressure of the wind, and dius its falling back prevented, when die force of the wind decreases. At the bottom of the wooden tube is an iron in- dex, which moves round a circular piece of wood fastened to the top of the pillar, on the pedestal, where the thirty-two points of die compass are described. We have annexed a representation of this machine : a is the pedestal ; /•, the pillar on which the iron axis is htted ; c, the circle of wood representing the points of the compass ; e, the wood- en tube upon its axis ■. f, the velum ; g, the graduated quadrant ; //, the counterpoise of the vane. The sub- joined rigure represents the velum, which may be taken otf: a is the plane of the velum ; t, the spring ; cc, the wooden radii ; d,d, the holes through which passes the pin, in the centre of the quadrant. ANE This instrument serves the foI« lowing useful purposes : 1. Hav«