The dry meter, on the other hand, is
very convenient, because it is not obstructed by the effects of frost,
and because it acts for years without requiring attention. It is not
susceptible of adjustment for measuring with so high a degree of accuracy
as a good wet meter, but its indications are sufficiently correct to fall
well within the legalised deviations already mentioned. Such errors,
perhaps, are somewhat large for so costly and powerful a gas as
acetylene, and they would be better reduced; but it is not so very often
that a dry meter reaches its limit of inaccuracy. Whether wet or dry, the
meter should be fixed in a place where the temperature is tolerably
uniform, otherwise the volumes registered at different times will not
bear the same ratio to the mass of gas (or volume at normal temperature),
and the registrations will be misleading unless troublesome corrections
to compensate for changes of temperature are applied.
THE GOVERNOR, which can be dispensed with in most ordinary domestic
acetylene lighting installations provided with a good gasholder of the
rising-bell type, is designed to deliver the acetylene to a service-pipe
at a uniform pressure, identical with that under which the burners
develop their maximum illuminating efficiency.
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