Fig. 5
Taking London as the place, take from the scale 381⁄2 deg., which is the difference between 90 and 511⁄2 deg. This distance must be marked off on the six-o’clock line from the points A and C. The rest of the construction is the same as for the horizontal dial, with the exception that the hours are limited to fourteen, viz. from five to seven o’clock, and are numbered backwards, or from left to right as in [Fig. 5]. The style is made as for the horizontal dial, but the angle C A B is to equal 381⁄2 deg. in the case of London, or the complement of the latitude. The base A D is to equal the length of the twelve-o’clock lines, measuring from the six-o’clock line to the inside line at the lower edge, or the lines A B and C D. In fixing this dial care must be taken to let it face due south.
Fig. 6
Fig. 7
Fig. 8
