The sweepers’ seasons of briskness and slackness, indeed, may be said then to be ruled by the thermometer, for the temperature causes the increase or diminution of the number of fires, and consequently of the production of soot. The thermometrical period for fires appears to be from October to the following April, both inclusive (seven months), for during that season the temperature is below 50°. I have seen it stated, and I believe it is merely a statement of a fact, that at one time, and even now in some houses, it was customary enough for what were called “great families” to have a fixed day (generally Michaelmas-day, Sept. 29) on which to commence fires in the sitting-rooms, and another stated day (often May-day, May 1) on which to discontinue them, no matter what might be the mean temperature, whether too warm for the enjoyment of a fire, or too cold comfortably to dispense with it. Some wealthy persons now, I am told—such as call themselves “economists,” while their servants and dependants apply the epithet “mean”—defer fires until the temperature descends to 42°, or from November to March, both inclusive, a season of only five months.
As this question of the range of the thermometer evidently influences the seasons, and therefore, the casual labour of the sweepers, I will give the following interesting account of the changing temperature of the metropolis, month by month, the information being derived from the observations of 25 years (1805 to 1830), by Mr. Luke Howard. The average temperature appears to be:—
| Degrees. | |
|---|---|
| January | 35·1 |
| February | 38·9 |
| March | 42·0 |
| April | 47·5 |
| May | 54·9 |
| June | 59·6 |
| July | 63·1 |
| August | 57·1 |
| September | 50·1 |
| October | 42·4 |
| November | 41·9 |
| December | 38·3 |
London, I may further state, is 2½ degrees warmer than the country, especially in winter, owing to the shelter of buildings and the multiplicity of the fires in the houses and factories. In the summer the metropolis is about 1¼ degree hotter than the country, owing to want of free air in London, and to a cause little thought about—the reverberations from narrow streets. In spring and autumn, however, the temperature of both town and country is nearly equal.
In London, moreover, the nights are 11·3 degrees colder than the days; in the country they are 15·4 degrees colder. The extreme ranges of the temperature in the day, in the capital, are from 20° to 90°. The thermometer has fallen below zero in the night time, but not frequently.
In London the hottest months are 28 degrees warmer than the coldest; the temperature of July, which is the hottest month, being 63·1; and that of January, the coldest month, 35·1 degrees.
The month in which there are the greatest number of extremes of heat and cold is January. In February and December there are (generally speaking) only two such extreme variations, and five in July; through the other months, however, the extremes are more diffused, and there are only two spring and two autumn months (April and June—September and November), which are not exposed to great differences of temperature.
The mean temperature assumes a rate of increase in the different months, which may be represented by a curve nearly equal and parallel with one representing the progress of the sun in declination.
Hoar-frosts occur when the thermometer is about 39°, and the dense yellow fogs, so peculiar to London, are the most frequent in the months of November, December, and January, whilst the temperature ranges below 40°.
The busy season in the chimney-sweepers’ trade commences at the beginning of November, and continues up to the month of May; during the remainder of the year the trade is “slack.” When the slack season has set in nearly 100 men are thrown out of employment. These, as well as many of the single-handed masters, resort to other kinds of employment. Some turn costermongers, others tinkers, knife-grinders, &c., and others migrate to the country and get a job at haymaking, or any other kind of unskilled labour. Even during the brisk season there are upwards of 50 men out of employment; some of these occasionally contrive to get a machine of their own, and go about “knulling,”—getting a job where they can.