To make a Cross Dial.—­A cross dial is one which shows the time of the day without a gnomon, by a shadow of one part of the dial itself, appearing upon another part thereof. Observe.—­In making this dial you need have no regard to the latitude of the situation, for that is to be considered in the placing, and not in the making of it. 1st.  Prepare a piece of wood or stone of what size you please, and fashion it in the form of a cross (see fig. 1) so that ab, bc, cd, de, eh, hi, ik, kl, lm, and ma, may be all equal:  the length of ef is immaterial, it may be more than double to a e. 2ndly.  Set one foot of your compasses in e and describe the arc h n, which divide into six equal parts for six hours, because it is a quarter of a circle; lay a ruler from e to the three first divisions, and draw the lines e o, e p, e q. 3rdly.  Now the position of this dial being such that its end a m must face the south, and the upper part of it or the line a f lying parallel to the equinoctial, it is evident that the sun at noon will shine just along the line a b, and m l; therefore you must place 12 at b and l, then from 12 to 3 P.M. the shadow of the corner a will pass along the line b c, therefore take from the quadrant h n, the distance h o, and set it from 12 to 1.  Take also h p and set it from 12 to 2, h q being equal to b c; at c you may place 3 where the shadow of the corner a goes quite off the dial at c, or 3 o’clock in the afternoon; at this time the shadow of the corner i will appear on the side h g at q or 3 o’clock, where place the figure 3; the shadow will then ascend to p at 4, to o at 5; at 6 there will be no shadow, the sun shining right along the line i h; place a VI also at the corner l, because it also shines along the line l k, and from 6 till 9, (if it be in a latitude where the sun continues up so late) the shadow of the corner at k is passing along the line l m:  therefore take the distances h o, &c., and set off from 6 to 7 and from 6 to 8, as before at 12, 1, and 2.  Then for the morning hours, the shadow of the corner c will enter upon the line a b at the point a, just at 3 o’clock in the morning, and if you draw lines from 7 and 8 parallel to a m, their terminations will point out 4 and 5.  Six o’clock is in the very corner opposite to 6 in the evening.  Parallel lines below the transverse piece drawn from 5, 4, 3, will indicate the proper places for 7, 8, 9.  It then remains to set off the same distances as before on line l k on which the shadow of m will point out 11, 10, and 9 o’clock; the dial will then be finished.