. My garden, its plan and culture together with a general description of its geology, botany, and natural history. Gardening. GARDEN TOOLS. 65. extreme power of the sun by day, but there are others to indicate the highest and lowest temperature of the air. .These are placed under protection of a little shed (fig. 78), so arranged that neither sun nor rain can affect the instruments. My scientific instruments were made by Messrs. Thornthwaite of Newgate Street. Visitors are requested never to touch these instruments; but, as I well know the tendency of all Englishmen to see with their fingers,
. My garden, its plan and culture together with a general description of its geology, botany, and natural history. Gardening. GARDEN TOOLS. 65. extreme power of the sun by day, but there are others to indicate the highest and lowest temperature of the air. .These are placed under protection of a little shed (fig. 78), so arranged that neither sun nor rain can affect the instruments. My scientific instruments were made by Messrs. Thornthwaite of Newgate Street. Visitors are requested never to touch these instruments; but, as I well know the tendency of all Englishmen to see with their fingers, two or three common thermo- meters are placed on the stand to draw away their attention from the real instruments of observation. Some years ago I designed a thermometer to use with an electric current to determine at a distance any deviation of limit of temperature in houses; thus a gardener may have, in his bed-room, an instrument to show the temperature of every plant-house. This was perfectly successful; but it has not been employed at my garden. The drying power of the air is estimated by the difference of temperature shown between a dry and a wet bulb thermometer; as the greater the difference, the greater the dryness of the atmosphere. The bulb is kept wet by a covering of silk, the end of which dips in dis- tilled water. This contrivance is called Mason's hygrometer, and i, shown in the centre of our meteorological observatory (fig. 78). It has always appeared to me advisable to determine the amount of evaporation which takes place in a definite time, as that has an important bearing upon vegetation. For this purpose I employ a tube graduated to one-tenth of an inch (fig. 79), which shows how much water evaporates per week. These evaporations are calculated to lead to much valuable information, and are nearly as important as thermometers. To determine the amount of rain which falls week by week, we use a rain-gauge, the result of 79. the observations of which is gi
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectgardening, bookyear18
