Miscellanies. 349 
locity on a curved road and the plain of the rails is horizontal, the 
flange of the fore wheel on the exterior rail is exposed to very great fric- 
tion, which operates as a retarding force, and injures both the car and 
the rail way. This friction is diminished, though not altogether re- 
moved, by giving to the exterior rail, the elevation which the velocity 
and radius require. In order to reduce the friction still further, or re- 
move it altogether, it would perhaps be advisable to increase by a 
small quantity the elevation obtained as above. It is evident that a 
car moving on the inclined plane AD, will tend by its own weight to 
approach A and recede from D. This will oppose the centrifugal force 
by which the flange is pressed against the rail D, and thus the fric- 
tion will be in whole or in part removed. I know it has been main- 
tained that the flange of the hind wheel on the interior rail produces 
as much friction as the flange of the exterior fore wheel. It may 
however be shown from various considerations, that if either of the 
hind wheels produces friction, it is rather the exterior one. Indeed 
we may suppose that motion is communicated to the hind wheels by 
a force which acts precisely in the same direction as if they were 
moved by animal power, the direction being nearly a tangent to the _ 
curve. ‘This being admitted, the flanges of the two exterior wheels 
sustain all the friction occasioned by curvature. It may be observ- 
ed however, that when the distance between the fore and hind wheels 
is comparatively very great, the direction of the force moving the 
hind wheels will vary considerably from the direction of a tangent, 
and consequently the friction will be diminished. 
MISCELLANIES. 
FOREIGN AND DOMESTIC. 
Extracted and Translated by Prof. Griscom. 
CHEMICAL AND MECHANICAL SCIENCE, 
With practical applications. 
1. Intcine—a remedy in intermittent fevers.—Doct. Emile Rous- 
shed his own observations, together with those 
Is, as well as 
all uniting in 
seau has just publi 
of eminent practitioners, in civil and marine hospita 
those of various private physicians no less estimable, 
ascribing to the leaves of the common Holly, (Hex aquifolium) great 
efficacy in the treatment of intermittents. They consider this indi- 
45 
Vou. XXII.—No 2. 
