A treatise on the climate amd meteorology of Madeira; / by the late J.A. Mason, M.D. ... edited by James Sheridan Knowles. To which are attached a review of the state of agricuture and of the tenure of land; by George Peacock. ... and an historical and descriptive account of the island, and guide to visitors; by John Driver.

  • Mason, J. A. (John Abraham), 1808?-1835 or 1836.
Date:
1850
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on the climate amd meteorology of Madeira; / by the late J.A. Mason, M.D. ... edited by James Sheridan Knowles. To which are attached a review of the state of agricuture and of the tenure of land; by George Peacock. ... and an historical and descriptive account of the island, and guide to visitors; by John Driver. Source: Wellcome Collection.

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    will be the same, the thermometer in the stem of the instrument will be proportionally higher or lower, according to the care taken to protect it from the different sources of radiation and reflection. This caution is particularly required in Madeira, where there is almost an absolute impossibility of making observations in the shade, entirely free from the influence of radiant caloric, given out from the various buildings. I have almost invariably found that between a thermometer placed in the shade, and another sus- pended in an ordinary room, out of the direct rays of the sun ; there are from four to five degrees of difference. On this account, when Professor Daniel’s hygro- meter is employed in Madeira, the temperature of the air ought to be taken—not from the tliermome- ter attached to the instrument—but from another thermometer, registering the same degree, under similar circumstances, as that included within the ball of the instruments; and protected as much as possible from every source of radiant or reflected heat; in order to avoid to the utmost, the arriving at erroneous results. In noticing these facts, it will be at once per- ceived that I do not wish to bring Mr. Daniel’s hygrometer into disrepute. I consider the data furnished by it, when in the hands of an experi enced meteorologist, of unimpeachable character. At the same time it is requisite to inform those who have not made this interesting branch of science n