MEANS OF COMMUNICATION. 11 
tunnel was completed with the exception of the descending road for the 
carriages, and was opened for foot passengers. The carriage road on each 
side is forty feet wide and descends fifty-seven feet in two turns of a spiral 
of 200 feet in diameter, the grade being thus very moderate. The archways 
are lighted by gas, and the temperature in them is but little different 
from that of the open air. 
The whole cost of the work, originally estimated at $800,000, amounted 
to $3,000,000, on account of the breaks and many other accidents ; and the 
excavation and removal of a cubic yard of earth cost on the average $16. 
According to a moderate estimate the income of the tunnel amounts to 
$100,000 annually. 
D. Raulroads. 
Roads with wheel-tracks of large blocks of dressed stone closely fitted 
were used early by the Egyptians and Indians in order to transport with 
more facility the great burdens they used in their structures, and a stone 
road of that kind led from Palmyra to Baalbec through the desert. The 
Romans had similar stone-tracks, for which they used granite, porphyry, 
and syenite ; but still the blocks were frequently crushed by the immense 
loads transported over them, and on that account stone-tracks gradually fell 
into disuse. 
About 300 years ago the first wooden railroads were built in Germany, — 
in the mines of the Hartz mountains. The track consisted of two parallel 
beams or sleepers of timber, between which the wheels ran on planks. The 
roads affording great facility, Queen Elizabeth employed German miners to 
construct similar ones in England in iron and coal mines. It often occurred 
that the carriages were thrown off the track by stones and other impedi- 
ments, in order to obviate which iron tires with exterior flanges were put 
on the wheels. The rapid wear of the wooden rails, which did not last over 
six years, caused in 1738 the employment of flat bars of cast iron, which 
were secured with spikes to the wooden rails. In 1770 the continuous 
wooden support was replaced by stones and the flat rails by prismatic ones 
(edge rails), and next came the Vignole or T-rails. In 1776 Carr proposed 
to support the rails on wooden cross-sills, and in 1797 Barnes employed 
blocks of stone in place of the latter. Since 1810 wrought iron has been 
used for rails instead of cast iron, and the rails may thus be made 
15-18 feet long, and much lighter than before when they were but 3-4 feet 
long. 
At first railroads were only introduced to facilitate the transportation of 
burdens by horse-power, one horse drawing as much on the railroad as eight 
on a common road. After the invention of the steam-engine, Dr. Robinson 
suggested in 1750 that it might be used as a motive power on railroads, but 
the idea was ridiculed as insane ; it was however pursued by Watt in 1769, 
and by Evans in North America in 1786, but without any practical attempt. 
It was only in 1802, after the invention of the high pressure steam-engine, 
that the inventors Trevithic and Vivian undertook the construction of a 
locomotive steam-engine, and in 1804 they obtained a patent for one to 
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