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carrying a convex lens, is fixed at the mouth of the vessel which contains the fluid. The axis of the screw is kept at right angles to the surface of the fluid by means of a level; and the relation of the surface to a fixed point in the scale of the instrument, is ascertained by the position of the screw at the instant when the surface of the lens attracts the fluid.
4. An instrument for measuring the magnitude of the drops of rain and the flakes of snow. This may
be done by ascertaining with a telescope of a given magnifying power, the greatest distance at which they are visible.
5. An instrument for measuring the angle at which rain falls. The rain is not always inclined to the quarter of the heavens to which the wind blows. If the lower stratum of air is moving slowly in one direction, and the upper stratum with a greater velocity in the opposite direction, the rain may be inclined to the quarter of the heavens from which the lower stratum of air blows.
6. A method of measuring the density of fogs and mists. This may be done by ascertaining the distance at which objects cease to become vis
7. A DIAPHANOMETER, for measuring the transparency of the air. An instrument of this kind has been invented and described by the celebrated M. Saussure.
8. A CYANOMETER, for measuring the blue colour of the sky. This instrument was invented by M. Saussure, who employed blue circles of paper, with different depths of colour. A much better instrument might be made, by enclosing a blue fluid between two plates of glass inclined to each other, so that the depth of colour at the places where the glasses are separated to the greatest distance,
may always exceed a little the greatest blueness of the sky. A screw, carrying a small circular opening along a scale, would then indicate the blue colour of the sky at any instant.
9. The form, altitude, and colour of the clouds ought to be carefully ascertained. Mr Howard, Dr Bostock, and Mr Forster, have proposed different appellations for clouds of different forms. Some fixed nomenclature should be established.
10. The size and appearance of halos, the height of meteors, the aurora borealis, and other phenomena of a temporary kind, should be well
11. A SKOTOMETER, for measuring the approach of darkness and its intensity, has been recently constructed.
In the following Meteorological Tables, we have endeavoured to present our readers with a full and accurate account of the state of the atmosphere at Edinburgh and London during the year 1810.
The Meteorological Journal for Edinburgh, which is the most valuable and correct that has yet been made in Scotland, was kept in the house, and under the superintendance, of a philosopher of distinguished eminence, to whom the writer of the present article is indebted for the liberty of making it public. It contains the height of the barometer to the thousandth part of an inch at nine o'clock in the morning; the state of the thermometer attached to the barometer at the same instant; the height of the mercury in the thermometer at eight o'clock in the morning, 12 o'clock noon, and 10 o'clock in the evening; the force and the direction of the wind; and the state of the weather, both in the forenoon and in the evening of each day.