London's Pulse: Medical Officer of Health reports 1848-1972
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Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
Holborn 1929
[Report of the Medical Officer of Health for Holborn Borough]
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TABLE VII. METEOROLOGY OF LONDON, 1929. (Deduced from observations at Greenwich under the superintendence of the Astronomer Royal)
| 1928. | Air Temperature. | Bright Sunshine. | Rain and other forms or Precipitation. | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Mean of- | Mean of A. & B. | Difference from Average.* | Daily Mean. | Difference from Average.* | Per cent. of possible. | Total Fall. | Difference from Average.* | ||
| A. | B. | ||||||||
| Maximum. | Minimum. | ||||||||
| °F | °F | °F | °F | hrs. | hrs. | % | m.m. | m.m. | |
| January | 38.9 | 31.0 | 34.9 | - 3.6 | 0.98 | -0.26 | 12 | 22 | -21 |
| February | 37.9 | 26.3 | 32.1 | - 7.7 | 1.90 | -0.14 | 19 | 10 | -30 |
| March | 55.4 | 32.7 | 44.1 | + 1.6 | 5.33 | + 1.93 | 45 | 1 | -43 |
| April | 54.7 | 36.2 | 45.5 | -2.1 | 4.38 | -0.64 | 32 | 29 | - 8 |
| May | 65.5 | 43.7 | 5.46 | + 0.6 | 7.77 | + 1.30 | 50 | 46 | + 2 |
| June | 68.7 | 48.9 | 58.8 | —1.1 | 6.68 | -0.02 | 41 | 31 | - 20 |
| July | 76.3 | 53.1 | 64.7 | + 1.2 | 8.12 | + 1.62 | 50 | 45 | - 12 |
| August | 74.1 | 52.1 | 63.1 | + 0.5 | 6.02 | + 0.18 | 42 | 54 | - 2 |
| September | 75.5 | 52.6 | 64.1 | + 6.1 | 6.51 | +1.56 | 52 | 4 | - 41 |
| October | 58.7 | 42.6 | 50.7 | + 0.5 | 3.37 | + 0.25 | 31 | 66 | + 1 |
| November | 51.5 | 39.0 | 45.3 | + 1.3 | 1.84 | -0.12 | 21 | 128 | + 70 |
| December | 48.1 | 38.5 | 43.3 | + 3.1 | 1.52 | - 0.46 | 19 | 115 | + 58 |
| Year | 58.8 | 41.4 | 50.1 | + 0.0 | 4.55 | + 0.50 | 37 | 551 or 21.69 ins. | — 45 or — l.77in. |
| *The averages used are obtained from observations extending over 35 years (1881-1915). | |||||||||
Ultra-Violet Rays.
The figures given in Table VIII have been supplied by the kindness of Professor Sir
Leonard Hill, M.B., F.R.S.
The information on which the table was compiled was obtained by the use in a number
of towns of Professor Hill's "test by fading" instrument. By this means the biologically
active ultra-violet rays are measured by the fading of Webster standard solution of acetone
and methylene blue. The solution is put into a quartz tube which is closed with a piece of
rubber tubing and a glass stopper. The tube is held by the stopper and the rubber tube in a
suitable clamp and placed in a vertical position with the pointed end upward, fastened to
a bamboo pole, if necessary, to raise it above all obstructions. At the end of 24 hours—
from 4 p.m. to 4 p.m.—the colour of the tube is compared with the colour of eight standard
tubes, filled with fixed and uubleaehable solution. The difference between the readings before
and after exposure gives a measurement of the biologically active ultra-violet rays. Exposed
to a constant source of ultra-violet rays the fading is proportional to the time of exposure.
The degrees of the colour scale are equal and biologically standardised. One unit of fading
is equal to two or four times the erythema (or skin reddening) dose, the sensitiority of the
skin varying in individuals.