Royal Society. ; 305 
mattérs. I am not sure whether the phenomena I have been 
describing, may not have been connected with its reappear- 
ance with increased brilliancy. I do not know whether there 
had been observed any connection between the aurora borealis 
and the decomposition of clouds, as appeated in this instance. 
As this singularly beautiful phenomenon must have been 
seen by many thousands beside myself, I should be glad to hear 
an account of it from some intelligent observers. ‘ 
Yours, &c. OxssERVATOR. 
P.S. On the morning of Sunday there was a good deal of 
rain; there was also some rain the two preceding days. For 
nearly two months before, very little rain had fallen. 
sth April, } 
To Messrs. Nicholson and Tilloch. 
LXVII. Proceedings of Learned Societies. 
ROYAL SOCIETY. 
March 24. Dr. Youne’s Remarks on the Employment of 
Oblique Riders, and on other Alterations in the Construction of 
Ships, were read. 3 
This paper contains a theoretical discussion of the mechanical 
properties of the different arrangements of timbers in ships and 
other fabries, according to their direction and modes of com- 
bination. The author first investigates the nature and magni- 
tude of the forces to be resisted, which are the weight, the pres- 
sure-of the water, the impulse of the wind, and the resistance of - 
the ground, or of a rock: and the action of the pressure in a 
‘longitudinal direction, as a cause of arching, which has not hi- 
therto been observed, is particularly examined. The force of the 
waves, both in a vertical and a transverse direction, is estimated 
as far exceeding in magnitude the more permanent causes of 
arching, although from its transitory nature it has been less 
commonly noticed as requiring particular counteraction. He 
next adverts to the insufficiency of a hasty view of the subject 
for the determination of the best arrangement, and shows that it 
is the stiffness of a fabric, and not its ultimate strength, that is 
most materially affected by the obliquity of arrangement, where 
the depth is given, and the fastenings are perfect; and that the 
question of the utility of oblique braces must be determined by 
the manner in which a ship usually breaks, whether by the altera- 
tion of the angular situation of the parts, or by the giving way 
of the fastenings. From actual observation he concludes that 
about half of the effect is generally produced in one way and 
half in the other ; and hence infers that the advantage of oblique 
timbers must be very considerable, provided they be sufficiently 
Vol. 45. No. 192. April 1814. @ U strong 
