is chiefly given off from their feet.  We can recall few occasions on which a plough that “carried” held a “burning scent.”  But little though we know of the mysteries of “scent,” it is generally agreed that the “steaming trail” emanates chiefly from the body and breath of a fox, even though on certain days there is no evidence of any scent, save on the ground.  It is probable, however, that on light ploughlands evaporation is so great when the sun is shining (unless the wind is sufficiently cold to counteract the heat of the sun and prevent rapid evaporation) that all scent from the body and breath of the fox, save that which happens to cling to the ground, is borne upwards and lost in the upper air. The hounds therefore have to fall back on whatever scent may remain clinging to the soil, those occasions of course excepted when the great density or gravity of the air prevents scent from rising and dispersing, and causes it to hang breast high.

After some years of careful experiment with the hygrometer and barometer, and after an intricate investigation of scent (that mysterious matter which is given off from the skin and breath of foxes), I have come to the conclusion that if we could get an Isaac Newton to “whip in” to a Tom Firr for about a twelvemonth, we might very likely come to know all about it.  In standing on ground whereon “angels fear to tread,” I am fully aware that I speak as a fool.  But let me state that it is on the barometer that I now place my somewhat limited reliance on a hunting morning, and not on the hygrometer, on the weight of the column of air on a given point of the surface of the earth, rather than on the state of the evaporations, the relative humidity, and the dew point.  And I have noticed that the best scenting days have been those when the thermometer has given readings from 38 up to 46 Fahrenheit in the shade.  A high and steady glass, an almost imperceptible east or north-east wind, with the ground soaked with moisture and no frost during the previous night, is the only combination of conditions under which scent on the grass is a moral certainty.  On the other hand, a low and unsteady glass, a warm, gusty south or west wind, with a hot sun, following a frost, or a day with cold showers, with bright, sunny intervals, or during the afternoon (but not always the morning) before a storm of wind or rain,—­such are the conditions which make so many of our attempts to hunt the fox by scent a miserable farce; yet even on these days hounds may run during some part of the day.  When the barometer is thoroughly unsettled there may be light local currents, perfectly imperceptible to man, yet felt by cows and sheep—­currents created like winds by a variation of temperature in different parts of any given field, and which will scatter the scent and spoil the sport.  These currents, rapid evaporation combined with a lack of steady atmospheric pressure, and that sticky state of soil which on ploughed land invariably follows a frost, and in a lesser degree affects grass, causing a fox to take his pad scent on with him (all the particles that do not cling to the ground having been diffused and lost in the air),—­these are the curses of modern hunting fields and the chief causes of bad scenting days.