A. The macintosh _prevents evaporation_, because the steam cannot escape through the air-tight fabric; and (as the _wet cannot evaporate_ from the clothes) no heat is absorbed from our bodies. Q. _Why do NOT SAILORS get COLD, who are so often wet all day with SEA-WATER?_ A. The _salt_ of the sea _retards evaporation_; and (as the heat of the body is drawn off _very gradually_) the sensation of cold is prevented. Q. _Why does SPRINKLING a HOT ROOM with water COOL IT?_ A. The heat of the room causes a _rapid evaporation of the sprinkled water_; and as the water evaporates, _it absorbs heat from the room_, and cools it. Q. _Why does WATERING the STREETS and roads COOL THEM?_ A. The hot streets and roads part with their heat _to promote the evaporation of the water sprinkled on them_. Q. _Why does a SHOWER of RAIN seem to COOL the AIR in summer-time?_ A. The earth (being wet with the rain) _parts with its heat to promote evaporation_; and as the _earth_ is cooled, it _cools the air_ also. Q. _Why is LINEN DRIED by being exposed to the WIND?_ A. The air (blowing over the linen) _promotes evaporation_, by removing the vapour from the _surface of the wet linen_, as soon as it is formed. Q. _Why is LINEN DRIED sooner in the open AIR, than in a confined room?_ A. Because the particles of vapour are more rapidly removed from the surface of the linen by evaporation. Q. _Why are WET SUMMERS generally SUCCEEDED by COLD WINTERS?_ A. Because the great evaporation (carried on through the wet summer) _reduces the temperature of the earth lower than usual_, and produces cold. Q. _Why is ENGLAND WARMER than it used to be, when AGUES were so common?_ A. Because it is _better drained_ and _better cultivated_. Q. _Why does DRAINING land promote WARMTH?_ A. Because it _diminishes evaporation_; in consequence of which _less heat_ is abstracted from the earth. Q. _Why does CULTIVATION increase the WARMTH of a country?_ A. 1st--Because _hedges and belts of trees_ are multiplied; 2ndly--Because the land is _better drained_; 3rdly--Because the land is _dug and ploughed;_ and 4thly--Because the vast _forests are cut down_. Q. _Why do HEDGES and BELTS of TREES promote WARMTH?_ A. Because they _retard evaporation_, by keeping off the _wind_. Q. _If belts of trees promote WARMTH, why do FORESTS produce COLD?_ A. 1st--Because they _detain and condense the passing clouds_: 2ndly--They prevent the access of both _wind and sun_: 3rdly--The soil of forests is always _covered with long damp grass, rotting leaves, and thick brushwood_: and 4thly--There are always many hollows in every forest _full of stagnant water_. Q. _Why do LONG GRASS and ROTTING LEAVES promote COLD?_ A. Because _they are always damp_; and the evaporation which they promote, _is constantly absorbing heat_ from the earth beneath. Q. _Why do DIGGING and PLOUGHING help to make a country WARM?_