^Notices. 
49 7 
so much as may be necessary to carry it off through a hole in the 
bottom. This object is effected by making the water enter hori- 
zontally into a cylindrical trough containing a solid cylinder with 
a space of 1 1-2 inches between them, near its top, and in the di- 
rection of a tangent to the cavity. The water, in passing through 
the annular space between the cylinders, and thence through a hole 
in the bottom, communicates a motion to the machine, which, by 
experiment, has been found from 7-10ths to 75- 1 GOths of the whole 
©alculated force of the falling water, a greater effect than any other 
machine has ever produced. 
Sir H. C, Englefield, Bart F. R. S. has invented a new transit 
instrument in which the telescope is placed with its axis perpen- 
dicular to the plane of the meredian, and the object seen by reflec- 
tion in a mirror placed at an angle of 45 degrees immediately in 
front of the object glass. When the telescope is properly placed, 
any part of the whole semicircle of the meredian may be seen by 
merely turning it on its axis. The same gentleman has also given 
a new mode of placing the transit instrument correctly. 
The following results have been given to the world by Joseph 
Read, M. D. of Cork, as deductions from several experiments 
made by him on the solar ray : 
1st. That incident light has never yet been decomposed ; and 
that Sir Isaac Newton, and other philosophers, only decomposed 
light reflected from opaque substances, or fringes of blue, red, 
and yellow. 
2d. That there are only three primary colours, blue, red and 
yellow by the mixture of which, either by the prism or painter, all 
the others are formed. 
8d. That Herschel, Leslie, Davy, Er.gleneld, and other philo- 
sophers, drew their conclusions relative to the heating power of 
the prismatic colours from erroneous data, viz. from experiments 
on reflected light, whose heat must, in a great measure, depend on 
the reflecting media, and, also, on the thickness and thinness of 
those parts of the prism through which the fringes pass. 
We give his deductions in his own words, and must confess that 
his experiments and reasoning furnish an apparently plausible ob- 
jection to the Newtonian theory of the separation of white light into 
rays of different colours. His second deduction is by no means 
new. Dr. Woollaston had already proved clearly that there were 
only three, or, at most, four colours in the spectrum ; and Dr. Read 
appears to have forgotten, or not to have known, his experiments 
