334 
PROCEEDINGS, 1859 — 1870. 
capital of tlie province. The great iiiilitar}- road Ijetween York and 
Manchester, traced out by Mr. Leyland, was shown to go by Slack 
and Castleshaw, with a brancli to Greetland and Littleboro'. Mr. 
Leyland gave a description of the discovery of a Roman altar 
at Thick Hollins, lying upon the height near Clay House. This altar 
had been erected at the beginning of the third century, about the 
time of the expedition of the Emperor Severus and his sons against 
the Caledonians, and bears an inscription to the effect that it Avas 
dedicated by Titus Aurelius Aurelanus to the God of the states of 
the Brigantes, and to the deities of the Emperor, on behalf of himself 
and his, in grateful remembrance of their undertakings. The altar 
was removed by Sir John Savile to Bi adley Hall, and has since been 
deposited in the British Museum. At Slack, which Mr. Leyland 
considered to be the site of the ancient Cambodunum, large numbers of 
the foundations of Roman houses have been found, and it has been 
a common practice for long past to dig for fence-stones from the 
foundations of these buildings. Subsequently to the reading of this 
paper investigations have been prosecuted at Slack, and the walls of a 
lloman bath, and houses with tiled floors have been unearthed. The 
objects discovered have since been placed in the Museum of the 
Halifax Literary and Philosophical Society. Discussing the direc- 
tion of the ancient Roman roads, Mr. Leyland expressed the opinion 
that whilst they would avail themselves of the ways previousl)^ 
formed by the Brigantes, it is extremely unlikely that their successors 
would desert the roads made by the greatest road-makers of anticpiity 
for the purpose of forming new ones, and he considered that most of 
those roads are still used at the present day. 
At a meeting of the Society held in March, lcS(57, Mr. Richard 
Reynolds described a Fire and Choke Damp Indicator invented by 
Mr. Ansell, of the Royal Mint. The action of this iustrument depends 
on the permeability of gases through more or less solid substances. 
The diffusion of fire-damp through a thin pellicle of india-rubber 
placed across the top of an iron funnel, provided with a U tube, to 
the end of which a piece of glass tube is fixed in brass, and to these 
the pole of a battery is attached. In the iron tube is placed niercur}", 
and when diffusion takes place the mercury is pressed up against 
