70 PHILOSOPHICAL TRANSACTIONS. [aNNO 1750. 



circle of figures on the card, which are the coinplements of the outer to go, and 

 consequently shew the distance from east or west. 



The azimuth of the stars may also be observed by night ; a proper light serving 

 equally for one observer to see the thread, and the other the degree on the card. 

 It may not be amiss to remark further, that in case the inner box should lose 

 its equilibrium, and consequently the index be out of the plane of a vertical 

 circle, an accurate observation may still be made, provided the sun's shadow be 

 distinct : for, by observing first with one end of the index towards the sun, and 

 then the other, a mean of the 2 observations will be the truth. 



Fig. 3, pi. 13, is a perspective view of the compass, when in order for ob- 

 servation. The point of view being the centre of the card, and the distance of 

 the eye 1 feet; ab is the wooden box; CD are two milled nuts; by means of 

 which the axes of the inner box and ring are taken from their edges, on which 

 they move, and the friction increased, when necessary ; e f is the ring that sup- 

 ports the inner box ; g h is the inner box ; and i is one of its axes, by which it is 

 suspended on the ring ef; kl is the magnet or needle ; and m a small brace of 

 ivory, that confines the cap to its place. See fig. 4. 



The card is a single varnished paper, reaching as far as the outer circle of 

 figures, which is a circle of thin brass, the edge being turned down at right an- 

 gles to the plane of the card to make it more stiff; o is a catgut line drawn down 

 the inside of the box; for determining the degree on the brass edge; pqrs is 

 the index bar, with its 1 stiles and catgut threads ; which being taken off from 

 the top of the box, is placed in two pieces, t and v, notched properly to receive 

 it ; w is a place cut out in the wood, serving as a handle. 



Fig. 4 is the card in piano, with the needle fixed on it ; being one third of the 

 diameter of the real card. 



Fig. 5 is a perspective view of the backside of the card; where ab represents 

 the turning down of the brass edge ; c is the under part of the ivory cap; d and 

 E are the '2 sliding weights to balance the card; and f and g, 2 screws that fix 

 the brass edge, &c. to the needle. 



Fig. 6 is the pedestal that supports the card, containing a sewing needle, 

 fixed in 2 small grooves to receive it, by means of the collet c, in the manner of 

 a port-creyon. At d the stem is filed into an octagon, that it may be the more 

 easily unscrewed. 



Description of a Fish* shown to the Royal Society by Mr. Ralph Bigland, March 

 11, 1749-50 : drawn up by C. Mortimer, M. D., Sec. R.S. N°495, p. 518. 



This fish is smooth skinned, has no scales, nor teeth. It has one erect fin on 

 • This fish is the Zeus Luna. /in. Si/st. Nat. Gmel. the Opah Pennt. Brit. Zool. 



