Copy 1

The construction and use of a thermometer for showing the extremes of temperature in the atmosphere, during the observer's absence. Together with experiments on the variations of local heat and other meteorological observations / By James Six.

  • Six, James, 1731-1793.
Date:
1794
Catalogue details

Licence: Public Domain Mark

Credit: The construction and use of a thermometer for showing the extremes of temperature in the atmosphere, during the observer's absence. Together with experiments on the variations of local heat and other meteorological observations / By James Six. Source: Wellcome Collection.

    41/122 (page 17)
    f ag 4 That a single instrument which indicates the ex- tremes ‘of both heat and cold in the observer’s ab- sence, should be altogether of as simple a con- struction, as, ene that shews neither, is more than ought, in reason, to be expected; nor is it neces- sary that it shouid, provided the: parts of which it is composed, be, with regard to matter and form, so adapted and combined, as completely to answer its design. ok By: resistance, of the index is meant, probably, ei- ther that the rising of the mercury will be, in some ‘measure, obstructed or retarded by it; or, that . the index, by the pressure’ of its spring, or other- wise, wil]. be prevented from. being carried up on the surface of the rising mercury, so readily as it ought td’ be, . But this. can never happen; be- cause the indexes, independent of the spring, are so'fitted as to pass freely up and down in the spi- rit; consequently sufficient space can. never, be wanting for the mercury to pass. by them, if they did not readily float on its surface. The pressure of the spring, in this case, acts as a small addition to the weight of the index, and is therefore ad- justed accordingly ; but w.H mo more obstruet the rising of the mercury, than vessels, left om the sea- shore by the tide, will obstruct the rising of it when it retuins. And even if it were possible for the c motion