To obviate this difficulty Felice Fontana of Florence (Saggio del real gabinetto di fisica e di storia naturale, 1 755) first proposed the use of spider webs in micrometers,' but it was not till the attention of Troughton had been directed to the subject by Rittenhouse that the idea was carried into practice.'
Two spider webs are stretched across the forks, one (t) being cemented in a fine groove cut in the inner fork k, the other (s) in a similar groove cut in the outer fork 1.
X 5 mm., the sides of this square being parallel spider webs 4" of arc apart; the size of the square is reckoned from centre to centre of these double webs.
Spider Webs: Spider webs have a wide variety of meanings including the passage of time, in the form of a cobweb.
Spiders and spider webs were popular themes in Victorian times, as they were thought to bring luck to the quilter.