=THE HORIZONTAL GARDEN DIAL= consists usually of a circular metal plate, divided into five-minute spaces, the hours, compass points, ornamental star, border and motto nicely engraved by hand, and a metal gnomon for casting the shadow to indicate the time of day. The larger dials, from 15 ins. in diameter, are divided to single minutes, but this is not always advisable, especially in low latitudes, as the minute divisions come too close together between the hours of 10 o’clock and 12 o’clock, and from 12 o’clock until 2 o’clock, so that the lines appear almost as one. When making a sundial of this description it is necessary for the maker to know the latitude, or name of the place where the dial is going to be fixed. =THE VERTICAL SUNDIAL=, which in construction is similar to a horizontal dial, is for placing in an upright position, such as on the wall of a church or house, or one of the side faces of a tall upright pillar. It should be made for, and fixed on, a wall having a southerly aspect, so as to receive as much sun as possible. Before constructing a vertical dial it is necessary for the maker to know the declination or true aspect of the wall, expressed in degrees, in addition to the latitude of the place. These figures must be absolutely correct, for the whole accuracy of the dial depends upon the figures given. The makers prefer to ascertain the declination themselves, for they alone then hold themselves responsible for the dial to indicate correct _solar_ time. There are many ways of measuring the length of a day in use in this country (the British Isles), but not one of them is perfect as a system for universal daily use. The three chief kinds of time used in this country are Greenwich mean time, Solar, or apparent time, and Sidereal, or star time; this latter is the only exact time and is used by astronomers alone. The time varies by several minutes between each of the methods mentioned. The difference between sundial time and clock time is due partly to the irregular motion of the earth travelling in its path round the sun. Sometimes it travels faster and sometimes slower. It is also due partly to the fact that the time shown by our clocks and watches, called _Greenwich mean time_, is purely artificial and imaginary, not agreeing with any natural time at all, nevertheless for commercial purposes, it answers very well. The sun crosses the meridian at Greenwich at 12 by the clock upon only four days in the year; on all other days it is either before or after the clock, the difference varying from a few seconds up to as much as a little over 16 minutes.