TRANSACTIONS. 
89 
construction of it. He gave it the name of an oil gas lamp ; not 
because it was lighted by gas formed at a temperature below 
that of flame, for this was common to all lamps, but because, as 
in the gas lights of the streets, the gas issued from a reservoir , 
and owed the perfection of its combustion not to an ascending 
current of hot air, but to the force with which it was propelled 
from the reservoir and carried the air along with it. It differed, 
however, from the common gas lights in these circumstances,— 
that the reservoir formed part of the burner; that the gas was 
formed as it was consumed; and that it was propelled, not by 
a vis a tergo and in a state of condensation, but by the expan¬ 
sive force of its own heat. In consequence of this circumstance 
the current of the gaseous jet was more rapid in proportion to 
the quantity of matter contained in it than in the common gas 
lights, whilst it was also at a much higher temperature, so that 
it could issue with a greater velocity, without being liable to blow 
itself out. The practical difficulty of the construction consisted 
in the obtaining a steady supply of oil, especially with the cheap 
oils. This difficulty had been in great measure surmounted, 
but the instrument was still imperfect, and had been charged 
by some accident that evening with a vegetable oil, from which 
a clear light could not be obtained. 
An Essay by Dr. Brewster on a new Analysis of Solar 
Light was read by Mr. Phillips. 
According to Sir Isaac Newton’s Analysis of Solar Light 
by the prism, white light consists of seven different colours, 
each of which has a peculiar range of refrangibility occupying 
distinct spaces in the prismatic spectrum, “ to the same degree 
of refrangibility ever belonging the same colour, and to the same 
colour ever belonging the same degree of refrangibility.” 
While examining the specific action of different coloured 
bodies in absorbing particular portions of the prismatic spec¬ 
trum, Dr. Brewster was led to observe that rays of two dif¬ 
ferent colours in the same spectrum had actually the very 
same degree of refrangibility, the one colour being super¬ 
imposed upon the other. By extending this inquiry, and 
availing himself of the aid of various methods of insulating 
rays which the prism could not separate, he was conducted 
to the new Analysis of Solar Light, which it was the object 
of this paper to explain and establish. The following propo¬ 
sitions contain a general view of the results. 
1. White Light, whether it be that of the sun or of artificial 
flames, consists of three simple colours only, Red, Yellow, and 
Blue , by the union of which all other colours are composed. 
