VOL. XLIV.] PHILOSOPHICAL TKANSACTIONS. 24S 



an inch, the point of the lever g moves 6 inches; and if the rod lengthens but 

 1 inch, the point g moves 6o. 



To this hygrometer he fixed a small index, such as is common in Mr. Haukes- 

 bee's barometers, to slip up and down on a wire, as is represented at k. 



Fig. 2 represents another method he employed to increase the power of the deal 

 rod. This may be fixed in a much smaller compass, and yet is no less capable of 

 showing the minute differences in the moisture or dryness of the air, than the 

 other The deal rod in this was managed and fastened in the same manner as 

 shown before. He also applied a lever abd to the top, exactly of the same dimen- 

 sions as in the other; but, instead of a second lever, he placed a graduated circle, 

 with an index, like that of the minute-hand of a clock. This he fixed to a small 

 axis, which was moved one way by a silken thread wrapped twice or thrice round 

 it, one end being tied to the longer end of the lever at d, and the other way by 

 the gravity of the weight w. And here, if the length of the index bs be 15 times 

 as long as the semidiaineter of the axis which the silk turns on, it is evident that 

 the sensibility of the rod's alteration will be increased 6o times, &c. 



The deal rod is strongly nailed down at n, both in the first and second draught; 

 but, in all other parts, they have free liberty of contraction or dilatation. 



He observed, that heat and cold have a considerable power of lengthening and 

 shortening the deal rod, as well as the moisture and dryness of the air; and this 

 at first sight would induce one to imagine, that it would be rendered almost use- 

 less; but it is really far otherwise; for, by placing it near a thermometer, it is 

 easily rectified with respect to its expansion or contraction, by heat or cold, at 

 the same time that it truly shows the various degrees of moisture or dryness in 

 the air. In short, it is an instrument made very easily, of materials to be got 

 almost every where, and of little cost. It is capable of being serviceable either by 

 sea or land, and may be placed in any direction. 



Concerning the Farina foecundans of the Yew-Tree. By R. Badcock, Esq. 



N°480, p. I89. 



March 3d, strolling round his garden in search of objects, Mr. B. observed a 

 yew-tree in blossom, but having at that time only the bud, fig. 3, pi. 6, which, 

 taken out of its case, may be seen with its umbilicus a, at fig. 4. That every 

 flower has its farina, has been justly advanced; and as it was his design to observe 

 that, he took a branch into the house ; but making but a slight observation at 

 that time, he laid it on half a sheet of brown paper in a warm drawer ; and, to 

 his great surprise, coming to examine it a few hours after, he found the whole 

 number of the buds blown out into full flower, and such a quantity of farina on 

 the paper, that it seemed more like a paper of brimstone than any thing else. 



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