TRANSACTIONS OF THE SECTIONS. 3 

The essential principle of the construction (see the annexed section in the plane 
of the meridian) consists in making the telescope (T) move about a point (C), at, or 
a little beyond, its eye-hole, instead of, as usual, about its middle point, by means 
of a counterpoise (W). The telescope projects sufficiently from the frame (F) which 
Be, 
A 

: carries it to allow room for the head of the observer ; and to this frame is attached 
the declination-axis (D), turning in supports from the lower frame (F’), through the 
arm of which passes the polar axis (P), fixed to a firm pier, and round which the 
whole is counterpoised by the weight (W’). 
When the whole is in the plane of the meridian the axis of the telescope coincides 
with the polar axis, and the point of intersection (C) of the polar and declination 
axes, is the position of the eye of the observer, or centre of motion, which is an 
_ tnvariable point in space for all altitudes and azimuths. A perpendicular dropped 
from this point gives a point (V) on the floor, at which a pivot is fixed, round which 
_ the observing couch (inclined at a constant angle) can revolve through a semicircle 
_ horizontally. The observer has only to push himself round in azimuth, and, in any 
_ given azimuth, he commands all altitudes in the plane of a circle at right angles to 
_ that azimuth, by simply turning his head from one side to the other. 
____ The possible objection of want of steadiness in the telescope is one which can 
si only be judged of by actual trial; but for telescopes of moderate size there seems no 
_ reason to apprehend that with well-constructed framing, axes, and counterpoises, 
sufficient steadiness might not be attained. 
§ The same principle is obviously, and with greater simplicity, applicable to small 
_ transits and moveable telescopes. In the latter case it has been successfully put to 
trial by the author. 

On the Friction of Water. By Rozert Rawson. 
__ The object of this paper is to ascertain the friction of water on a vessel or other 
floating bodies rolling in water. For this purpose experiments have been made 
upon a cylindrical model whose length is 30 inches, diameter 26 inches, and weight 
_255°43 lbs. avoirdupois, in the following manner. ‘The cylinder was placed in a 
iene in the first place, without water, and made to vibrate on knife-edges passing 
_ through the axis of the cylinder ; a pencil projecting from the model in the direc- 
tion of the axis of the cylinder on the surface of another moveable cylinder marked 
_ out upon paper placed upon this last cylinder the amplitude of each oscillation. 
& 
