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THE PNEUMATIC DESPATCH. 
BY S. J. MACKIE, E.G.S. 
U NDERGROUND London ill the course of a few years 
will be quite as wonderful as London above ground. 
The great arteries of the main- drainage, now the most 
wonderful of our present subterranean labours, will perhaps 
twenty years hence have to cede their supremacy and give 
place to something even more marvellous. Passing over the 
intricate net-works of gas and water pipes and electric wires, 
we have already the first instalment of underground passenger 
locomotion in the Metropolitan Railway, and the first instal- 
ment of a more extraordinary means of transit for goods and 
merchandise, in the short length of pneumatic pipe between 
the Euston Square terminus of the North-Western line and 
the North-Western district post-office. What the science of 
hydrostatics is for water, pneumatics is for air, and the 
Pneumatic Despatch Company is a commercial company with 
large capital, formed for the simple purpose of blowing or 
sucking gigantic pellets of merchandise through long iron 
tubes. We say simple, for everything is simple now-a-days 
to the increased intelligence of the nation ; and there is not 
an educated person who would not at the first description 
understand the main nature of the pneumatic despatch. The 
pneumatic tube has been compared by a popular writer to a 
boy's pea-shooter. The comparison is scarcely right. The 
pneumatic apparatus is more nearly comparable to the wheel- 
bellows our housemaids use in blowing up their fires. Still, 
the common pea-blower, or the longer South American Indian's 
blow-pipe, affords a good expression of the nature of the 
operation. The pea is put into the blower, or the dart into the 
blow-pipe, and a puff of the breath sends them through and 
projects them sharply from the other end. But it would be 
rather awkward to have the pellet- carriage ejected violently 
from the orifice of the pneumatic tube, like a cylindrical 
cannon-shot from a cannon's mouth. The carriages must 
come out gently, or damage would be done. It is easy to 
explain the manner in which the pneumatic despatch is prac- 
tically worked. In the common domestic wheel-bellows, by 
the turning of a handle at the side of the bellows, a fan- 
