chusetts, who have
recently issued a very suggestive circular, accompanied by numerous
examples of track construction for railway bridges. If this circular
receives proper attention, it is sure to produce good results.

Another point which has often been neglected, is making sufficient
provision to resist the force of the wind. A tornado, such as is not
uncommon in this country, will exert a force of 40 pounds per square
foot, which upon the side of a wooden bridge, say of 200 feet span,
and 25 feet high, and boarded up as many bridges are, would amount to
a lateral thrust of no less than 100 tons; and this load would be
applied in the worst possible manner, i.e., in a series of shocks.
There have been many cases in this country where bridges have been
blown down; and a case recently occurred where an iron railroad
bridge of 180 feet span, and 30 feet high, and presenting apparently
almost no surface to the wind, was blown so much out of line that the
track had to be shifted. The recent terrible disaster at the Firth of
Tay was, no doubt, due to this cause.

At the time of the Tariffville catastrophe, it was gravely stated at
the coroner's inquest, and by railroad officers who claimed to know
about such things, that the disaster was caused by the tremendous
weight of two locomotives which were coupled together, and it was
stated that one engine would have passed in safety; and directly
afterwards the superintendent of a prominent railroad in New England
issued an order forbidding two engines connected to pass over any
iron bridges. It is all very well for a company to issue such an
order, so far as it may give the public to understand that it is
determined to use every precaution against disaster; but such an
order may have the effect of creating a distrust which really ought
not to exist. If a railway bridge is not entirely safe for two
engines, it is certainly entirely unsafe for one engine and the train
following; the only saving in weight by taking off one engine being
the difference between the weight of that engine and the weight of
the cars that would occupy the same room. For example, a bridge of
200 feet span will weigh 1,500 pounds per lineal foot. An engine and
its tender will weigh 60 tons in a length of 50 feet, and a loaded
freight-train may easily weigh 2/3 of a ton per lineal foot. The
total weight of the span, with two engines, and the rest of the
bridge covered with loaded freight-cars, would thus be