106 Notices of the Proceedings of 



The friction at the axis may be rendered almost insensible, by 

 suspending the instrument on a single point. 



The registering part of the instrument exhibited, consisted of 

 a light vertical arm attached to the tube at the axis of motion. 

 At its lower extremity was attached a delic-ite glass tube, be- 

 ing one of those used for containing the leads supplied along 

 with Mordan's pencils ; inside of the tube there was a light- 

 pointed spine or bristle, so as to move freely up and down t< 

 and rest upon a surface beneath the tube. This surface was a 

 thin and long moveable plate of transparent mica. The pre- 

 ponderance iii the thermometer makes the point move across 

 this plate. On the underside of it, lines are to be drawn per- 

 pendicular to the direction of the point's movement, and at in- 

 tervals*corrcsponding to the divisions of the thermometric 

 scale. Thus the movement of the point across this plate in- 

 dicates the temperature. The plate itself is made to move 

 lenglhways> under the marking point, by means of a watch or 

 timepiece. And across the ihermometric divisions, on its 

 under side, are drawn other lines, marking the divisions of 

 time. When the instrument is set to work, the smooth upper 

 surfuce of the plate of mica is blackened in the smoke of a 

 lamp, aud properly disposed under the marking point, which, 

 by resting upon it, will, under the influence of its own move- 

 ment from variations of temperature, and the movement of the 

 plate by the watch, trace a distinct waving line on the 

 blackened surface ; the intersections of which, with the di- 

 visions on the under-side, point out the rate and period of the 

 variations of temperature. The plate of mica was bent to a 

 cylindric surface, so as to accommodate the circular movement 

 of the marking point. It was shown that the traces could be 

 advantageously received upon a concave spheric conoid, kept 

 in continued revolution. The advantages of using mica in 

 delicate measurements, or for scales of instruments, was also 

 illustrated. 



Aug. 31. — There was announced as presented by Mr. Ebden, 

 a specimeu of the Macacou or Madagascar Cat. — Capt. Bance 

 presented a report respecting the models of Anchors, sent by 

 Captain Evalt of Port Elizabeth ; in which he showed, that 

 the contrivance proposed as a modification of the common 

 anchor, would prevent it from keeping so fast a hold of the 

 ground, in consequence of the shank being jointed, or moving 

 in the plane of the arms, upon an axis at the crown. There 

 was presented a^copy of a Memoir on Steam-boats, by Captain 

 Pole «f His Majesty's ship Maidstone, with remarks thereupon, 

 by Monsr. Faragust of the College at iPort Louis. This 



