Sir Thomas Browne, treating of Errors regarding Numbers, observes: “True
it is that God made all things in number, weight, and measure; yet
nothing by them, or through the efficacy of either. Indeed, our days,
actions, and motions being measured by time (which is but _motion
measured_), whatever is observable in any, falls under the account of
some number; which, notwithstanding, cannot be denominated the cause of
these events. So do we unjustly assign the power of action even unto
time itself; nor do they speak properly who say that time consumeth all
things; for time is not effective, nor are bodies destroyed by it, but
from the action and passion of their elements in it; whose account it
only affordeth, and, measuring out their motion, informs us in the
periods and terms of their duration, rather than effecteth or physically
produceth the same.”[2]
Time can only be measured by motion: were all things inanimate or fixed,
time could not be measured. A body cannot be in two places at the same
instant; and if the motion of any body from one point to another were
regular and equal, the divisions and subdivisions of the space thus
marked over would mark portions of time.
The sun and the moon have served to divide portions of time in all ages.
The rising and setting of the sun, the shortening and lengthening of the
shadows of trees, and even the shadow of man himself, have marked the
flight of time. The phases of the moon were used to indicate greater
portions; and a certain number of full moons supplied us with the means
of giving historical dates.
Fifteen geographical miles, east or west, make one minute of time. The
earth turning on its axis produces the alternate succession of day and
night, and in this revolution marks the smallest division of time by
distances on its surface.
If each of the 360 degrees into which the circumference of the earth is
divided, be subdivided into twenty-four hours, it will be found that 15
degrees pass under the sun during each hour, which proves that 15
degrees of longitude mark one hour of time: thus, as Berlin is nearly 15
degrees east of London, it is almost one o’clock when it is twelve at
London.
Time, like bodies, is divisible nearly _ad infinitum_. A second (a mere
pulsation) is divided into four or five parts, marked by the vibrations
of a watch-balance; and each of these divisions is frequently required
to be lessened an exact 2880th part of its momentary duration. It is,
however, impossible to see this; for Mr. Babbage, speaking of a piece of
mechanism which indicated the 300th part of a second, tells us that both
himself and friend endeavoured to stop it twenty times successively at
the same point, but could not be confident of even the 20th part of a
second.
It has been said that many simple operations would astonish us, did we
but know enough to be so; and this remark may not be inapplicable to
those who, having a watch losing half a minute per day, wish it
corrected, though they may not reflect that as half a minute is the
2880th part of 24 hours, each vibration of the balance, which is only
the fifth part of a second, must be accelerated the 2880th part of its
instantaneous duration; while to make a watch, losing one minute per
week, go correctly, each vibration must be accelerated the 1008th part
of its duration, or the 50,400th part of a second.[3]
Among the early methods of measuring Time, we must not omit to notice
Alfred’s “Time-Candles,” as they have been called. His reputed
biographer, Asser, tells us that Alfred caused six tapers to be made for
his daily use: each taper, containing twelve pennyweights of wax, was
twelve inches long, and of proportionate breadth. The whole length was
divided into twelve parts, or inches, of which three would burn for one
hour, so that each taper would be consumed in four hours; and the six
tapers, being lighted one after the other, lasted twenty-four hours. But
the wind blowing through the windows and doors and chinks of the walls
of the chapel, or through the cloth of his tent, in which they were
burning, wasted these tapers, and consequently they burnt with no
regularity; he therefore designed a lantern made of ox or cow horn, cut
into thin plates, in which he enclosed the tapers; and thus protecting
them from the wind, the period of their burning became a matter of
certainty. But the genuineness of Asser’s work is doubted,—so the story
is discredited. Nevertheless, there is nothing very questionable in
Alfred’s reputed method; and it is curious to see that an “improvement”
was patented so recently as 1859, which consists in graduating the
exterior of candles, either by indentation or colouring at intervals,
and equal distances apart, according to the size of the candles. The
marks are to consist of hours, half-hours, and, if necessary,
quarter-hours; the distance to be determined by the kind of candle used.
Bishop Wilkins, in his _Mathematical Magic_, in the chapter relating to
“such engines as did receive a regular and lasting motion from something
belonging to their own frame, whether weights or springs, &c.,” quotes
Pancirollus, “taken from that experiment in the multiplication of wheels
mentioned in Vitruvius, where he speaks of an instrument whereby a man
may know how many miles or paces he doth go in any space of time,
whether or no he pass by water in a boat or ship, or by land in a
chariot or coach. They have been contrived also into little pocket
instruments, by which, after a man hath walked a whole day together, he
may easily know how many steps he hath taken.” More curious is “the
alarum, mentioned by Walchius, which, though it were but two or three
inches big, yet would both wake a man and of itself light a candle for
him at any set hour of the night. And those great springs, which are of
so great force as to turn a mill (as some have contrived), may be easily
applied to more various and difficult labours.”
Occasionally, in these old curiosities, we trace anticipations of some
of the scientific marvels of the present day. Thus, when the Grand Duke
of Tuscany, in 1669, visited the Royal Society at Arundel House, he was
shown “a clock, whose movements are derived from the vicinity of a
loadstone; and it is so adjusted as to discover the distance of
countries, at sea, by the longitude.” The analogy between this clock and
the electrical clock of the present day is not a little remarkable. The
Journal-book of the Society for 1669 contains many allusions to “Hook’s
magnetic watch going slower or faster according to the greater or less
distance of the loadstone, and so moving regularly in every posture.” On
the occasion of the visit of illustrious strangers, this clock and
Hook’s magnetic watches were always exhibited as great curiosities.[4]
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Footnote 2:
_Vulgar and Common Errors_, book iv. chap. xii.
Footnote 3:
_Time and Timekeepers._ By Adam Thomson, 1842.
Footnote 4:
See Weld’s _History of the Royal Society_, vol. i. pp. 220, 221.
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