[Report 1895] / Medical Officer of Health, Torquay Borough.

  • Torquay (England). Borough Council.
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: [Report 1895] / Medical Officer of Health, Torquay Borough. Source: Wellcome Collection.

    22/38 (page 20)
    with the zodiacal frame, and in the patterns for use in different latitudes, it has been much improved by Professor Stokes, F.R.S., the Greenwich and Kew Observers, and Messrs. Beckley, Cassella, and Negretti and Zambra. There is at present a great difference of opinion as to the exactitude of the two instruments, which give a difference of sunshine duration of from 5 to 16 per cent., the Jordan Instrument always giving in the monthly totals the larger amount; but occasionally in the daily totals less than the Campbell-Stokes Instrument. It is alleged that the Campbell-Stokes measures only bright sunshine, and that the Jordan measures sunlight as well as sunshine; but from the work done here for the past 8 years with the Photographic Instrument I have never traced or measured any sunlight on the charts, after they have been immersed in water, face upwards, according to the instructions issued to Observers by the Royal Meteorological Society. The Photographic Instrument is more troublesome than the Campbell-Stokes Instrument, but taking the different states of the atmosphere into consideration all the year round, it is the more accurate and sensitive instrument of the two. These instruments, which are also Sun dials, for the measurement of sunshine and of time, are open to great improvement, and doubtless will in the future be made as exact in measurement and definition as the telescope, the spectroscope, the barometer, and the thermometer. ANEMOMETER. The Anemometer, for registering the velocity and direc¬ tion of the wind and the time of its various changes, is a Robinson embossing, self-recording instrument by Casella. The general principle of this instrument is the invention of Dr. Robinson, of Armagh, in which four hemispherical cups revolve with the pressure of the wind. The very ingenious registering parts of the instrument and also the vane, are new, and were designed by Mr. Beckley, of Kew Observatory, and Mr. Casella. The force-and-die principle of em¬ bossing is the means of registration here adopted. The paper employed for receiving the hourly velocity and direction marks, is blue in colour and formed of narrow strips, rolled