. The Family tutor . of the malady that so soon put anend to his career of active usefulness. Itis also said that his health had been in-jured by exhalations from the poisons withwhich he experimented. Strong and trueto the end, the final effort of his dyingwill was expressed in an order for the post-mortem examination of his body his last contribution to the progress ofscience. He left 120,000 francs to foundprizes for the solution of questions mostimportant to the advancement of Toxi-cology, and of medicine generally. Spiders Thread. —Austrian papersstate that a merchant of Vienna has lately
. The Family tutor . of the malady that so soon put anend to his career of active usefulness. Itis also said that his health had been in-jured by exhalations from the poisons withwhich he experimented. Strong and trueto the end, the final effort of his dyingwill was expressed in an order for the post-mortem examination of his body his last contribution to the progress ofscience. He left 120,000 francs to foundprizes for the solution of questions mostimportant to the advancement of Toxi-cology, and of medicine generally. Spiders Thread. —Austrian papersstate that a merchant of Vienna has latelypresented to the Industrial Union of thatcapital, the details of a series of experi-ments made by him to manufacturespiders thread into woven tissues. Thethread is wound on a reel, and two dozenspiders produce, in six minutes, a beauti-ful and delicate thread, two thousand feetin length. The stuffs manufactured arespoken of as being far superior to thoseof silk in beauty and delicacy of fabric. NATURAL \¥ig. 180. THE SCREW.—CONTINUED. When the thread of a screw works in the teeth of a wheel, as shown in Fig. 180,it constitutes an endless screw. An important use of this contrivance is in the engine for dividing graduated circles. The screw is also used toproduce slow motions, or to measure, hy the advance of itspoint, minute spaces. In the spherometer, represented inFig. 5, page 4, we have an example of its use. For all these purposes where slow motions have to begiven, or minute spaces divided, the efficacy of the screwwill increase with the closeness of its thread. But there issoon a practical limit attained ; for, if the thread be toofine, it is liable to be torn off. To avoid this, and toattain those objects almost to an unlimited extent,Hunters screw is often used. It may be understood from Fig. 181. It consists of ascrew, working in a nut, a b. To a moveable piece, e, a secondscrrfw, c, is affixed. This screwworks in the interior of a, whichis hollow, and
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Keywords: ., bookcentury1800, bookdecade1850, bookpublisherlondo, bookyear1851
