Geological Survey of Great Britain. 235 
Publication of the Maps and Sections. 
The maps of the Ordnance Survey, which are employed 
for the field-work, serve also as the foundation for the publi- 
cation of the geological maps. They are prepared on the 
scale of one inch to the English mile of 800 Vienna fathoms, 
or 23 times larger than our maps of the Staff of the Quarter- 
master General. The originals are engraved on copper, 
whilst, for the geological maps, an electrotype copy is taken, 
and upon those reproduced plates the boundary-lines are 
afterwards engraved. The colouring is done by hand. 
The sections also are engraved on copper from the draw- 
ings prepared by the Survey. In all of them the same scale 
is employed both for heights and distances, so that the pic- 
ture, instead of appearing distorted, is true to nature. The 
sections also are coloured by hand. 
Works at the Museum in London. 
With the labours for the preparation and publication of 
the maps and sections are connected those which are carried 
on at the Museum in London. Their full development, how- 
ever, will not come into play before the completion of the 
aboye-mentioned new building in Piccadilly. Through a 
handsome portico one enters the principal apartment, occu- 
pying by far the greater part of the whole edifice, which is 
170 feet long, 80 feet wide, and 80 feet high. It receives its 
light through a glass roof from above; two galleries, one 
above the other, are attached to the wall, in order to increase 
the space disposable for the exhibitions of the collections. 
Beneath the great room, and lighted up by the upper light 
which passes through a large circular opening in the middle 
of the room, is a lecture theatre, in which it is proposed to 
give, during the winter, lectures on geology, paleontology, 
and chemistry, and, it is hoped, afterwards on mining and 
metallurgy. In the same manner as in France, where the 
Ecole des Mines is situated in Paris, they will here proceed 
on the persuasion, that the theoretical part of education 
which the miners should have, can best be obtained in the 
