METEOROLOGY.

The table above contains the results of the observations made at Kingston, Jamaica, between June, 1880, and May, 1890, inclusive. Between June, 1880, and December, 1886, the readings were taken at intervals of eight hours, namely, at 7 a.m., 3 p.m., and 11 p.m., local mean time; the daily means of pressure, temperature, dewpoint, humidity, &c, were assumed to be the means of the three eight-hourly readings, but since January, 1887, the readings have been taken at 7 a.m. and 3 p.m. only; and the daily means were deduced by applying to the 7 a.m. and 3 p.m. readings their proper reductions; and from the daily means the monthly means given in the table have finally been deduced.

The readings were taken with great care and regularity, and they were all corrected for instrumental errors.*

In the second column the Barometric Pressure is of course referred to the sealevel.

In the seventh column the wind is stated to be S.E., and this is in consequence of the regularity of the daily sea-breeze, which is almost invariably S.E. at Kingston. In the eighth column the Dew point has been found from the Dry and Wet-bulb thermometers by means of Glaisher's factors; of course Wet-bulb and Tension-ofVapour columns could have been added, but it seemed useless to fill up the table with columns easily deducible the one from the other.

In the tenth column the amount of cloud is given as a percentage of the whole sky. In the eleventh and twelfth columns are given for the period in question the average monthly Rainfall at the Public Works Office, Kingston, and for the whole Island,—the latter being deduced from about 150 stations.

The remaining columns give for each month the average number of deaths in Kingston from a few groups of diseases, and the average totals; they have been taken from the returns published monthly by Mr. S. P. Smeeton, the Registrar-General. The following are some of the relations existing among the different columns.

(i.) PRESSURE AND RAINFALL.

If the Barometric Pressure be compared,-not with the Kingston Rainfall on account of its highly local character, but with the general Island Rainfall, it will be seen that a certain relation exists:

Rainfall 50 (30.100-pressure) or in words, if the pressure during any month be subtracted from 30.100, and if the difference be multiplied by 50, the product will not be far from the Rainfall in inches.

This remarkable relation requires much further consideration, for which we have at present neither space nor time.

(ii.) TEMPERATURES.

The mean temperature does not greatly differ from half the sum of the maximum and minimum temperatures. In order to make the agreement closer we must take into account the Range, or difference between the maximum and minimum, the humidity, and the amount of cloud which covers the sky.

The maxima and minima given in the table were deduced from daily readings, and their differences give the daily range; but by picking out of the original record or register the highest and lowest temperatures for each month we get the absolute max. and min. To prevent confusions the absolute max. and min, were not inserted in the table; their averages are, however, 4a above and below the max, and min. deduced from daily readings.

Again in the interval between June, 1880, and May, 1890, the highest temperature was 96 1.0 recorded on the 12th September, 1880, and the lowest temperature was 56.7.o recorded on the 4th December, 1887.

And lastly the Mean Daily Temperature is here given for each complete year :—

*The Thermometers were exposed in the Stevenson screens over a grass lawn, four or five feet above the ground.

(iii.) VAPOUR.

The humidity of the air is the ratio of the amount of vapour present to the amount necessary for saturation, -saturation being taken as 100; so that humidity indirectly measures the drying power of the air.*

By comparing the Dew-point with the Minimum Temperature we see that there is an almost constant difference of about half a degree. The nights in Kingston therefore cool down until the temparature of the air four or five feet above the ground is a little above the Dew-point; but on the ground the temperature is below the Dewpoint, dew is precipitated, latent heat given out, and the further fall of temperature arrested.

We must now consider the connections between these Meteorological results and the number of deaths in Kingston.

(iv.) INFANTILE DISEASES.

Under this heading is given the number of deaths in Kingston each month of the year from infantile diseases not otherwise specified in the books of the Registrar General.

By comparing the numbers in this column with the total monthly numbers in the last column, it will be seen that the former are fairly proportional to the latter, although, indeed, their variation from their mean or average is larger.

Consequently whatever cause systematically affects the total monthly numbers, the same cause affects young children rather than adults.

(v.) TOTAL MONTHLY NUMBERS.

The total number of deaths vary on the average with considerable regularity from month to month; the maximum, 139, occurs in March; the minimum, 79, occurs in September.

This variation is intimately connected with the temperature; and remembering that there must always be a considerable interval of time between such a cause and such an effect, it appears that the maximum occurs after the lower temperatures, and that the minimum occurs after the higher temperatures; or in other words, the deathrate greatly increases after our cool season, and greatly diminishes after our warm

season.

As in the year 1881, there were in Kingston only 5,000 white people out of a total population of 38,566, it is to the black and colored people that the above result chiefly applies; and again as the fall of temperature during the cooler months is really very small, the large increase in the number of deaths must be chiefly due to the lives led by many of the poorest people,-to their sleeping under open sheds and dilapidated roofs; and it would therefore seem possible to reduce the Kingston death-rate in the course of time.

(vi)-FEVER.

There are but few deaths from this cause, and they are distributed throughout the year with considerable uniformity. One maximum occurs in July after the May rains, and another occurs in November, December, and January after the October rains. These maxima are due to malaria set free by the drying-up of the ground after heavy rains.

In many countries in the tropical parts of the earth it is dangerous to disturb the soil, as for instance in the Gold Coast Colony in Africa, because the soil teams with malaria; and so it must have been in the earlier days of Jamaica when the land was first cleared of forests and when the soil was first turned up for the cultivation of the sugar-cane; but now, we, for the most part, only feel the effect of water returning upwards from considerable depths below the surface of the ground; for with the water ascend those specific disease-germs which produce malarial fever when they can secure a footing in the blood and develop specific organisms.

"The germs of these organisms float about in the air from place to place and gain positions enabling them to enter the blood of some animal organism, say man, where they can grow and flourish, provided they are able to successfully encounter their

100.

If the drying power of the air were measured from 0 to 100, Humidity plus drying power, would always be

mortal foes, the white corpuscles of the blood. If these white corpuscles are strong and vigorous, they will overpower the foreign growth and kill it. If on the other hand they are weak and feeble, and the germs very numerous, the foreign growth may get a secure footing and spread luxuriantly changing the character of the fluids of the body, coagulating, it may be, the albumen, and otherwise setting-up the unnatural and abnormal display of functions which we call disease."*

We have thus dwelt upon the cause of malaria in places which may be far removed from swamps and morasses, not on account of its importance to Kingston, but because of its widely spread influence in Jamaica.

(vii)-LUNG DISEASES.

The number of deaths from this cause is tolerably constant throughout the year. A maximum occurs in January, and another in July; but after both these maxima there seems to be a small reaction, and the minima speedily follow.

(viii.) DYSENTERY AND DIARRHEA.

Deaths from these diseases are intimately connected with the Minimum Temperature; a few cold nights in Kingston are certain to produce either or both these diseases; and their virulence depends upon the extent to which the temperature falls. But some allusions must be made to predisposing causes, of which rain seems to be the most important in Jamaica,-the people get wet and do not change their clothes,—a cold night sets in, and disease is the immediate consequence.

Thus there were rains in December, 1880, which produced Dysentery and Diarrhoea in January, 1881; but it was not until the cold nights of January, that these diseases became serious and caused the death of 72 persons during the three following months. Again in December, 1881, and the early part of 1882 there were no rains and very little Dysentery and Diarrhoea.

We must not expect to find complete agreement between our Meteorological returns and those of the Registrar General; but we hope that the out-lines of the agreement have been correctly sketched, and that the importance of the subject has been duly pointed out.

DECREASE OF TEMPERATURE WITH ELEVATION.

The meteorological results found for Kingston are generally applicable to all the low-lying land round the shores of Jamaica; but of course the temperature decreases on the hills and mountains in the interior. The rate of decrease is much the same as in other countries, namely: about 1° F. for every 300 feet of elevation; but as Max., Mean and Min. temperature, have to be considered, it will be as well to reproduce the table given in Weather Report No. 75.

But whether this table be consulted in the interest of agriculture or in the establishment of a health resort, it must be remembered that all the surroundings have

* Nature, Vol. 31, p. 267.

first to be considered; and then when any site has been proposed as suitable, its Max., Mean, and Min. temperatures may be easily deduced from its approximate elevation.

THE ISLAND RAINFALL.

The Rainfall is now fairly well registered in Jamaica, almost entirely by voluntary observers; but unfortunately the guages are very unequally distributed over the island. To meet this difficulty the island is divided into four Divisions, and month by month the Rainfall is deduced for each Division, the Island Rainfall being simply the mean of the four Divisions.

It appears that while the May and October rains are everywhere strongly marked, the northern part of the island has winter rains in November, December and January, the southern part has summer rains in August and September, and each part is further divided by the amount of rainfall, thus giving the four divisions.

The North-eastern Division is cut off by a straight line drawn from Port Morant to St. Ann's Bay; it includes the lofty range of the Blue Mountains, and their continuation as the hills of St. Mary; it faces the rain-bringing winds of winter; and it has a large rainfall in November, December and January, as well as in May and October. This division has the greatest annual rainfall.

The Northern Division includes the parishes of St. Ann, Trelawny and St. James. It is that part of the island which lies to the north of those broken ranges of hills which run through the centre of the island in a direction more or less parallel to the Blue Mountain range. The annual rainfall is less than in the first division, but it has the same characteristics.

Tho West-central Division stretches in the same direction from Chapelton to Green Island. It is deprived of the greater part of the winter rains by the two former divisions, whose hills precipitate the abundant vapour in the east-north-easterly winds; but it has well-marked summer rains in August and September, as well as the usual rains in May and October. It has a larger annual rainfall than the Northern Division. The last and Southern Division has the same characteristics as the third, but the annual rainfall is much smaller.

In the preface to Sir Hans Sloane's Natural History of Jamaica we find that he alluded to the May and October rains; to the winter rains on the north side, to the summer range on the central hills and to the small rainfall on the southern plains. Consequently the characteristics of the rainfall have not altered for at least two hundred years.

This leads us to the consideration of the constancy of the amount of rainfall, and at length we are able to give some information on this important subject. According to the two following tables the average rainfall over the island was about sixtyseven and a half inches for the first decennial period from 1870 to 1879, while for the second decennial period from 1880 to 1889 the average rainfall over the island was sixty-six and a half inches, or one inch less. But as these results are greatly effected by "flood" rains, the only wonder is that they are so nearly equal.

Again, it will be seen that there has been a curious increase in the rainfall in the second decennial period in the West-central and Southern Divisions, while there has been a larger decrease in the North-eastern and Northern Divisions, as though the whole rainfall system had been shifted more to the south. All such variations are for the most part temporary, and the present decennial period may show just the opposite.