Observations upon lightning, and the method of securing buildings from its effects. In a letter to Sir Charles Frederick, &c. &c. &c / by B. Wilson ... and others.

  • Benjamin Wilson
Date:
1773
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Licence: Public Domain Mark

Credit: Observations upon lightning, and the method of securing buildings from its effects. In a letter to Sir Charles Frederick, &c. &c. &c / by B. Wilson ... and others. Source: Wellcome Collection.

    62/88 (page 48)
    THESE lart: experiments are a ftrong confirmation of the reiyiing principle, tiowever, we will endea¬ vour to illuftrate it farther by the following argu¬ ment, which is founded upon fome obfervations of Sir Ifaac Newton’s, refpedting the preffure of con¬ vex-glailes ; and which I have taken from the letter to Epinus^ mentioned in the 38 th page. When a bladder is well blown up, and fecured properly, it will yield or give‘ way, and change its form in that part againft which any given preffure is exerted. And upon removing the preffure, the bladder will immediately recover its firft form. This yielding or giving way of the form, and then afterwards recovering it, proves an elaftic fubftance exifting within the bladder, and between the two tides v/here the preffure is employed. In like manner, when two glafs prifms, or the objedl glaffes of two long telefcopes prefs upon each other with their own weight only, phiiofophers know, by the phcenomena of light, that they do not touch : and that there muft be fomething betw^een the glaffes to keep them at a diftance. They alfo know, by the like phcenomena, that more preffmg is ones, upon the convertabillty of condu6l!ng fubftances into non- Condudiors of the eledfric fluid, in the' Phil. I'ranf. Vol. 51, p. 87. “ Havino; dried a Piece of Portland flone, I found it condudfed “ perfedfly well ; but upon powdering and fealing it up in a glais tube, in which was a wire at each end) it became a perfedf re- fiifler or non-condu6for like the metallic calces; which feems to fliew, that the refiftance to the paflage of the eledtric fluid may be iricreafed, by increafing the number of furfaces.