338 An Astronomical Machine, the Tellurium. 
face, the outline being a logarithmic spiral. He found also that 
certain portions of these might be cut off without diminishing 
the effect. With respect to ascertaining the friction of the screw 
on the water, great difficulty exists; but he would refer to his 
experiments, published some years ago in the Philosophical 'Trans- 
actions, in which he measured the friction of the water against 
a body revolving in it, by the time which a given weight took 
to descend ; this body consisted of rings, and he found that the 
friction or resistance through the water did not increase in propor- 
tion to the number of rings. 
The following papers were also communicated. 
. Report on railway constants, by Dr. 
Remarks on the connexion which exists between improvements in pitwork oa 
the oie oF te ma ae in Cornwall, by Mr. Enys. 
ruscott’s plan for reefing paddle-wheels, by Mr. Cha 
a plan of disengaging and reconnecting the paddle-wheels 4 aman 
by Mr. J. Grantham 
na floating breakwater, by Capt. Taylor, R.N. 
Further report of the committee on the forms of vessels, by Mr. J. S. Russell: 
* On an improved sight bite rifles and other fire-arms, ~ Mr. C. 'T. Coathupe. 
On Capt. Couch’s chock channels, by Mr. Snow Har 
On Arnott’s stove, and the construction of Neosat os, and their anblice- 
tion to the aati of ventilation, peor. J. N. Hearde 
Report of the committee on altel constants, by Mr. Edward Woods. 
On the granite quarries of Dartmoor, and their railways and machinery, by Mr. 
W. Fohescn 
Report of the committee for applying a principle of Dynamometrical admeasure- 
ment, invented by M. Poncelet, to the construction of a permanent indicator for 
steam-engines, 
On a system of trussing for the roadways of eapension bridges, by Mr, Rendel. 
On the Plymouth breakwater, by Mr. Wm. Stu 
_ Arr. XIV.—An Asironomical Machine, the Tellurium ; by 
Epwin C. Leepom, M. D., of Plymouth, Penn. 
_ Tuts isa machine for representing the motions of the earth 
and moon. ‘The earth, whose axis has its proper obliquity to the 
ecliptic and keeps its parallelism, revolves round the sua in an 
ellipsis similar to the natural orbit, and moves with such a velo- 
city that an i imaginary line joining the centres of these two bod- 
ies, the latter being situated in one of the foci of the orbit of the 
former, describes equal areas in equal times. The diurnal rota- 
tions of the planet are also. shown, each complete turn on its axis 
