Physical and medical climate and meteorology of the west coast of Africa

By the term climate is to be understood the condition of a Definitions. place as regards the various complex phenomena connected Climate. with the soil, the water, and the atmosphere.

When soil is referred to in a climatic point of view, it is soil. intended to include all that portion of the earth's crust which, under certain conditions, is capable of affecting health.

Dr Parkes gives the four following as the conditions necessary for soil to affect health, viz.:

1. Its conformation and elevation.

2. The vegetation covering it.

3. Its mechanical structure, which influences absorption and radiation of heat, reflection of light, absorption of water, movement of water over and through the soil, passage of air through soil, formation of dust.

4. Its chemical structure, which acts especially by altering the composition of the air over the soil, or the water running through it.

To which may be added the aspect of a place, and the amount of sunshine and light it receives.

There are only two considerations by which the supply of water. water might affect health, viz., its quality and its quantity.

The climatic conditions of the air or atmosphere by which Atmosphere.

Meteorology.

Meteorolo

gical Instruments.

health can be affected might be arranged under the following headings, viz.:-1. Its temperature; 2. Its humidity; 3. Its movement; 4. Its weight; 5. Its composition; and 6. Its electrical condition.

Of late, the meteorology of tropical climates has occupied the attention of many physicians; and the more our knowledge is increased as to its various influences in enhancing or mitigating diseases, the better shall we be able to conquer many seeming difficulties in their treatment. Unfortunately, as yet meteorology has not been turned to extensive practical advantage; but every year new facts are discovered, and old principles greatly elucidated; and the time is not far distant when the ascertained meteoric causes of disease will be so displayed before the public mind, that each individual will, by the force of public opinion, find it incumbent on him to employ the best hygienic remedies for the removal of those causes.

I differ from the assertion of Dr Mason Good, that "of all the subdivisions of general philosophy, meteorology is the least entitled to the name of science; and, consequently, physicians need not blush at being incapable of turning to account the supposed influence of the planets, or of unfolding and tracing the origin and capricious courses of epidemics and pestilence." This subject opens a wide field for investigation, which would repay any physician who labours to develope the untold facts connected with the meteoric origin and progress of pestilential and other diseases. Meteorology treats especially of the atmosphere -the different changes it undergoes during the course of the year characterised as the seasons-the degree of heat and cold -of saturation and of the state of the wind, as well as the barometric pressure, and, consequently, treats of subjects which are the ascertained causes of most of the diseases we meet with in tropical climates. In these several bearings it affords objects of interest to the agriculturist, the botanist, the naturalist, the navigator, and the physician.

To carry on meteorological observations, various instruments are required; and I shall here give the official instructions

issued by the Army Medical Department for reading the meteorological instruments supplied by that Department. They are as follow:

The observer should make himself thoroughly acquainted with the scale of every instrument, especially with that of the barometer, and its attached vernier, and by frequent comparisons ascertain that he and his deputy read the instruments alike, and record the observations accurately.

All observations must be recorded exactly as read. The corrections are to be made only at the end of each month on the "means" of the "sums."

Barometrical observations must be recorded to the third decimal place; thermometrical, to the first decimal. When the readings are exactly to the inch or degree, the places for the decimals must be filled up with ciphers.

The observations should be made as quickly as possible, consistently with perfect accuracy, and the observer must avoid breathing on the instruments, particularly the dry and wet bulbs, and maximum thermometers.

Barometer Readings.-Note the temperature of attached thermometer in degrees only; by means of the thumb-screw at the bottom adjust the mercury in the cistern to its proper level, the point of the ivory cone, which should just touch the mercury without breaking the surface; then bring the zero line of the vernier to the level of the apex of the column of mercury, and read off in the manner described at page 15 and 16 of Sir H. James's "Book of Instructions."

Thermometer Readings.-The scales are divided to degrees. only, but these are so open that the readings can be determined to the tenth of a degree. Practice and attention will ensure

accuracy.

Maximum Thermometer in Shade.-The maximum thermometer must be hung at such a distance (2 or 3 inches) from the water vessel of the wet bulb thermometer, that its readings may not be affected by evaporation.

In hanging the maximum, care must be taken that the end

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