_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.