VOL. XXXI.] PHILOSOPHICAL TRANSACTIONS. 479 



point e, to ascend up to g, and to take up the space eg; and in like manner 

 the arch f h will be the projection of the column ph. From hence it is evident, 

 that the reason why the triangular streams ascended at first only from the 

 northern parts of the heavens, was this : the fund of matter ep was not yet 

 arrived by its motion to the line cd. After it had passed that line, it is plain 

 they must appear to ascend from all quarters. A great number of columns 

 being therefore disposed to emit light, at the same time, caused that perfect 

 canopy described above. The reason why that canopy descended lower in the 

 north than in the south, was this: the shining columns which had not yet 

 passed the line cd, were more numerous and more remote from it than those 

 which had passed it; for if the point e be farther distant from cd than the 

 point p, the arch ac must needs be less than the arch sf. An irregular gust of 

 wind blowing on and shaking the columns I suppose was the cause of that 

 trembling which appeared in the triangular streams, and the cause also which 

 destroyed that fine appearance of the canopy. The slender circular waves, seen 

 at the same time, might also be explained from the same cause. I need not 

 detain you any longer by endeavouring to make out some other particulars of 

 this unusual appearance, I fear I have been already too tedious. However I 

 will not omit to mention a very easy contrivance, by which the thing may be 

 tolerably well represented to view. Take a hoop, and round about it fasten 

 several straight sticks, parallel to each other, but all inclined to the plane of 

 the hoop, hold this plane parallel to the horizon, and in that posture move it 

 with the sticks over a candle; then the shadows of the sticks on the ceiling of 

 your room will converge to a point not directly over the candle, as they would 

 have done had the sticks been perpendicular to the plane of the hoop, but to 

 the point in which a line drawn from the candle parallel to the sticks shall inter- 

 sect the plane of the ceiling. 



A Letter of Dr. John Qiuncy to the late learned Mr. Sam. Moreland, F. R. S. 

 concerning the Operation of Medicines. N° 365, p. 71. 



There is nothing in this letter of sufficient importance for republication. 



An Account of an extraordinary Cramp and Fistula. By Dr. Steigerthall, 



F, R. S. N° 365, p. 79. 



John Henry Oizmann, aged 3 1 years, was 1 5 years of age when the follow- 

 ing misfortune befel him. 



He felt a spasm or cramp in his left hip, and the lower part of his leg. As 

 this pain seized him pretty often, a surgeon applied several plasters to the place, 



