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REGISTERING OPERATIONS.

therefore, been contrived for measuring and registeringthe length of the goods as they pass rapidly throughthe hands of the operator, and all chance of erro-neous counting is thus avoided.

(47.) Perhaps the most useful contrivance of thiskind, is one for ascertaining the vigilance of a watch-man. It is a piece of mechanism connected with aclock placed in an apartment to which the watchmanhas not access ; hut he is ordered to pull a stringsituated in a certain part of his round once in everyhour. The instrument, aptly called a tell-tale, informsthe owner whether the man has missed any 7 , and whathours during the night.

(48.) It is often of great importance, both for re-gulations of excise as well as for the interest of theproprietor, to know the quantity of spirits or ofother liquors which have been drawn off by thosepersons who are allowed to have access to the vesselsduring the absence of the inspectors or principals.This may be accomplished by a peculiar kind of stop-cock,'— which will, at each opening, only dischargea certain measure of fluid,—the number of timesthe cock has been turned being registered by acounting apparatus accessible only to the master.

(49.) The time and labour consumed in guagingcasks partly filled, has led to an improvement which,by the simplest means, obviates a considerable incon-venience, and enables any person to read off, on ascale, the number of gallons contained in any vessel,as readily as he does the degree of heat indicatedby his thermometer. A small stop-cock is insertednear the bottom of the cask, which it connects witha glass tube of narrow bore fixed to a scale on the