On the Economy of Machinery and Manufactures - Charles Babbage (interesting books to read in english .TXT) 📗

Chapter 8

Registering Operations

 

65. One great advantage which we may derive from machinery is

from the check which it affords against the inattention, the

idleness, or the dishonesty of human agents. Few occupations are

more wearisome than counting a series of repetitions of the same

fact; the number of paces we walk affords a tolerably good

measure of distance passed over, but the value of this is much

enhanced by possessing an instrument, the pedometer, which will

count for us the number of steps we have made. A piece of

mechanism of this kind is sometimes applied to count the number

of turns made by the wheel of a carriage, and thus to indicate

the distance travelled: an instrument, similar in its object,

but differing in its construction, has been used for counting the

number of strokes made by a steamengine, and the number of coins

struck in a press. One of the simplest instruments for counting

any series of operations, was contrived by Mr Donkin.(1*)

 

66. Another instrument for registering is used in some

establishments for calendering and embossing. Many hundred

thousand yards of calicoes and stuffs undergo these operations

weekly; and as the price paid for the process is small, the value

of the time spent in measuring them would bear a considerable

proportion to the profit. A machine has, therefore, been

contrived for measuring and registering the length of the goods

as they pass rapidly through the hands of the operator, by which

all chance of erroneous counting is avoided.

 

67. Perhaps the most useful contrivance of this kind, is one

for ascertaining the vigilance of a watchman. It is a piece of

mechanism connected with a clock placed in an apartment to which

the watchman has not access; but he is ordered to pull a string

situated in a certain part of his round once in every hour. The

instrument, aptly called a tell-tale, informs the owner whether

the man has missed any, and what hours during the night.

 

68. It is often of great importance, both for regulations of

excise as well as for the interest of the proprietor, to know the

quantity of spirits or of other liquors which have been drawn off

by those persons who are allowed to have access to the vessels

during the absence of the inspectors or principals. This may be

accomplished by a peculiar kind of stop-cock—which will, at

each opening, discharge only a certain measure of fluid the

number of times the cock has been turned being registered by a

counting apparatus accessible only to the master.

 

69. The time and labour consumed in gauging the contents of

casks partly filled, has led to an improvement which, by the

simplest means, obviates a considerable inconvenience, and

enables any person to read off, on a scale, the number of gallons

contained in any vessel, as readily as he does the degree of heat

indicated by his thermometer. A small stop-cock connects the

bottom of the cask with a glass tube of narrow bore fixed to a

scale on the side of the cask, and rising a little above its top.

The plug of the cock may be turned into three positions: in the

first, it cuts off all communication with the cask: in the

second, it opens a communication between the cask and the glass

tube: and, in the third. It cuts off the connection between the

cask and the tube, and opens a communication between the tube and

any vessel held beneath the cock to receive its contents. The

scale of the tube is graduated by pouring into the cask

successive quantities of water, while the communication between

the cask and the tube is open. Lines are then drawn on the scale

opposite the places in the tube to which the water rises at each

addition, and the scale being thus formed by actual

measurement,(2*) the contents of each cask are known by

inspection, and the tedious process of gauging is altogether

dispensed with. Other advantages accrue from this simple

contrivance, in the great economy of time which it introduces in

making mixtures of different spirits, in taking stock, and in

receiving spirit from the distiller.

 

70. The gas-meter, by which the quantity of gas used by each

consumer is ascertained, is another instrument of this kind. They

are of various forms, but all of them intended to register the

number of cubic feet of gas which has been delivered. It is very

desirable that these meters should be obtainable at a moderate

price, and that every consumer should employ them; because, by

making each purchaser pay only for what he consumes, and by

preventing that extravagant waste of gas which we frequently

observe, the manufacturer of gas will be enabled to make an equal

profit at a diminished price to the consumer.

 

71. The sale of water by the different companies in London,

might also, with advantage, be regulated by a meter. If such a

system were adopted, much water which is now allowed to run to

waste would be saved, and an unjust inequality between the rates

charged on different houses by the same company be avoided.

 

72. Another most important object to which a meter might be

applied, would be to register the quantity of water passing into

the boilers of steamengines. Without this, our knowledge of the

quantity evaporated by different boilers, and with fireplaces of

different constructions, as well as our estimation of the duty of

steamengines, must evidently be imperfect.

 

73. Another purpose to which machinery for registering

operations is applied with much advantage is the determination of

the average effect of natural or artificial agents. The mean

height of the barometer, for example, is ascertained by noting

its height at a certain number of intervals during the

twenty-four hours. The more these intervals are contracted, the

more correctly will the mean be ascertained; but the true mean

ought to be influenced by each momentary change which has

occurred. Clocks have been proposed and made with this object, by

which a sheet of paper is moved, slowly and uniformly, before a

pencil fixed to a float upon the surface of the mercury in the

cup of the barometer. Sir David Brewster proposed, several years

ago to suspend a barometer, and swing it as a pendulum. The

variations in the atmosphere would thus alter the centre of

oscillation, and the comparison of such an instrument with a good

clock, would enable us to ascertain the mean altitude of the

barometer during any interval of the observer’s absence.(3*)

 

An instrument for measuring and registering the quantity of

rain, was invented by Mr John Taylor, and described by him in the

Philosophical Magazine. It consists of an apparatus in which a

vessel that receives the rain falling into the reservoir tilts

over as soon as it is full, and then presents another similar

vessel to be filled, which in like manner, when full, tilts the

former one back again. The number of times these vessels are

emptied is registered by a train of wheels; and thus, without the

presence of the observer, the quantity of rain falling during a

whole year may be measured and recorded.

 

Instruments might also be contrived to determine the average

force of traction of horses—of the wind—of a stream or of any

irregular and fluctuating effort of animal or other natural

force.

 

74. Clocks and watches may be considered as instruments for

registering the number of vibrations performed by a pendulum or a

balance. The mechanism by which these numbers are counted is

technically called a scapement. It is not easy to describe: but

the various contrivances which have been adopted for this

purpose, are amongst the most interesting and most ingenious to

which mechanical science has given birth. Working models, on an

enlarged scale, are almost necessary to make their action

understood by the unlearned reader; and, unfortunately, these are

not often to be met with. A very fine collection of such models

exists amongst the collection of instruments at the University of

Prague.

 

Instruments of this kind have been made to extend their

action over considerable periods of time, and to register not

merely the hour of the day, but the days of the week, of the

month, of the year, and also to indicate the occurrence of

several astronomical phenomena.

 

Repeating clocks and watches may be considered as instruments

for registering time, which communicate their information only

when the owner requires it, by pulling a string, or by some

similar application.

 

An apparatus has recently been applied to watches, by which

the hand which indicates seconds leaves a small dot of ink on the

dial-plate whenever a certain stop or detent is pushed in. Thus,

whilst the eye is attentively fixed on the phenomenon to be

observed, the finger registers on the face of the watch-dial the

commencement and the end of its appearance.

 

75. Several instruments have been contrived for awakening the

attention of the observer at times previously fixed upon. The

various kinds of alarums connected with clocks and watches are of

this kind. In some instances it is desirable to be able to set

them so as to give notice at many successive and distant points

of time, such as those of the arrival of given stars on the

meridian. A clock of this kind is used at the Royal Observatory

at Greenwich.

 

76. An earthquake is a phenomenon of such frequent occurrence,

and so interesting, both