Fortunately both one and the other appearance can be very easily

accounted for without calling in the aid of the supernatural. At a

recent meeting of the Photographical Society it was shown that an image

may often be so deeply impressed on the glass that the subsequent

cleaning of the plate, even with strong acids, will not completely

remove the picture. When the plate is used for receiving another

picture, the original image makes its reappearance, and as it is too

faint to be recognisable, a highly susceptible imagination may readily

transform it into the image of a departed friend. The ‘double’ is

generated by the well-known property of double refraction, obtained by

a lens under certain circumstances of unequal pressure, or sometimes by

inequalities in the process of annealing. So vanish two ghosts which

might have been more or less troublesome to those who are ready to see

the supernatural in commonplace phenomena. Will the time ever come when

no more such phantoms will remain to be exorcised?

(From the _Daily News_, March 2, 1869.)

_THE OXFORD AND CAMBRIDGE ROWING STYLES._

Whatever opinion we may have of the result of the approaching contest

(1869), there can be no doubt that this year, as in former years, there

is a striking dissimilarity between the rowing styles of the dark blue

and the light blue oarsmen. This dissimilarity makes itself obvious

whether we compare the two boats as seen from the side, or when the

line of sight is directed along the length of either. Perhaps it is in

the latter aspect that an unpractised eye will most readily detect the

difference I am speaking of. Watch the Cambridge boat approaching you

from some distance, or receding, and you will notice in the rise and

fall of the oars, as so seen, the following peculiarities—a long stay

of the oar in the water, a quick rise from and return to the water,

the oars remaining out of the water for the briefest possible interval

of time. In the case of the Oxford boat quite a different appearance

is presented—there is a short stay in the water, a sharp rise from and

return to it, and between these the oars appear to hang over the water

for a perceptible interval. It is, however, when the boats are seen

from the side that the meaning of these peculiarities is detected, and

also that the fundamental distinction between the two styles is made

apparent to the experienced eye. In the Cambridge boat we recognise the

long stroke and ‘lightning feather’ inculcated in the old treatises

on rowing: in the Oxford boat we see these conditions reversed, and

in their place the ‘waiting feather’ and lightning stroke. By the

‘waiting feather’ I do not refer to what is commonly understood by slow

feathering, but to a momentary pause (scarcely to be detected when the

crew is rowing hard) before the simultaneous dash of the oars upon

the first grip of the stroke.[15] And observing more closely—which,

by the way, is no easy matter—as either boat dashes swiftly past, we

detect the distinctive peculiarities of ‘work’ by which the two styles

are severally arrived at. In the Cambridge crew we see the first part

of the stroke done with the shoulders—precisely according to the

old-fashioned models—the arms straight until the body has fallen back

to an almost upright position; then comes the sharp drop back of the

shoulders beyond the perpendicular, the arms simultaneously doing

their work, so that as the swing back is finished, the backs of the

hands just touch the ribs in feathering. All these things are quite in

accordance with what used to be considered the perfection of rowing;

and, indeed, this style of rowing has some important good qualities

and a very handsome appearance. The lightning feather, also, which

follows the long sweeping stroke, is theoretically perfect. Now, in

the case of the Oxford crew, we observe a style which at first sight

seems less excellent. As soon as the oars are dashed down and catch

their first hold of the water, the arms as well as the shoulders of

each oarsman are at work.[16] The result is, that when the back has

reached an upright position, the arms have already reached the chest,

and the stroke is finished. Thus the Oxford stroke takes a perceptibly

shorter time than the Cambridge stroke; it is also, necessarily,

somewhat shorter in the water. One would, therefore, say it must be

less effective. Especially would an unpractised observer form this

opinion, because the Oxford stroke seems to be much shorter in range

than it is in reality. _There_ we have the secret of its efficiency.

It is actually as long as the Cambridge stroke, but is taken in a

perceptibly shorter time. What does this mean but that the oar is taken

more sharply, and, therefore, much more effectively, through the water?

Much more effectively so far as the actual conditions of the contest

are concerned. The modern racing outrigger requires a sharp impulse,

because it will take almost any speed we can apply to it. It will

also retain that speed between the strokes, a consideration of great

importance. The old-fashioned racing-eights required to be continually

under propulsion. The lightning-feather was a necessity in their

case, for between every stroke the boat would lag terribly with a

slow-feathering crew. I do not say, of course, that the speed of a

light outrigged craft does not diminish between the strokes. Anyone who

has watched a closely contested bumping-race, and noticed the way in

which the sharply cut bow of the pursuing boat draws up to the rudder

of the other as by a succession of impulses, although either boat seen

alone would seem to sweep on with almost uniform speed, will know that

the motion of the lightest boat is not strictly uniform. But there is

an immense difference between the almost imperceptible loss of way of a

modern eight and the dead ‘lag’ in the old-fashioned craft. And hence

we get the following important consideration. Whereas with the old

boats it was useless for a crew to attempt to give a very quick motion

to their boat by a sharp, sudden ‘lift,’ this plan is calculated to be,

of all others, the most effective with the modern racing-eight.

It may seem, at first sight, that, after all, the result of the

Cambridge style should be as effective as that of the other. If arms

and shoulders do their work in both crews with equal energy—which we

may assume to be the case—and if the number of strokes per minute is

equal, the actual propulsive energy ought to be equal likewise. A

little consideration will show that this is a fallacy. If two men pull

at a weight together they will move it farther with a given expenditure

of energy than if first one and then the other apply his strength to

the work. And what is more to the purpose, they will be able to move

it faster. So shoulders and arms working simultaneously will give a

greater propulsive power than when working separately, even though in

the latter case each works with its fullest energy. And not only so,

but by the simultaneous use of arms and shoulders, that sharpness of

motion can alone be given which is essential to the propulsion of a

modern racing-boat.

I have said that the two crews are severally rowing in the style

which has lately been peculiar to their respective Universities. But

the Cambridge crew is rowing in that form of the Cambridge style which

brings it nearest to the requirements of modern racing. The faults of

the style are subdued, so to speak, and its best qualities brought

out effectively. In one or two of the long series of defeats lately

sustained by Cambridge the reverse has been the case. At present, too,

there is a certain roughness about the Oxford crew which encourages the

hopes of the light blue supporters. But it must be admitted that this

roughness is rather apparent than real, great as it seems, and it will

doubtless disappear before the day of encounter. I venture to predict

that the ‘time’ of the approaching race, taken in conjunction with the

state of the tide, will show the present crews to be at least equal to

the average.[17]

(From the _Daily News_, April 1869.)

FOOTNOTES:

[15] The grip is never properly caught without the pause; but anything

beyond a momentary pause is a bad fault in style.

[16] I write this with full knowledge that many Oxford men deny the

fact. I have rowed behind Cambridge, Oxford, and London strokes, and

have several times taken the place (number 2 thwart) of a London

waterman in a four (‘stroked’ by John Mackinney) training for the

Thames Regatta. So that I have had ample opportunities for comparing

different rowing styles; and I am satisfied that the main defect of

the real Cambridge style was (and perhaps is) an _exaggeration_ of the

sound rule that a boat should be propelled rather by the body than

by the arms. The very swing in a Cambridge boat shows that this must

be so. On the other hand, the Thames watermen do too much arm-work;

and hence seem to double a little over their oars. I once rowed with

some Cambridge friends from London nearly to Oxford and back, taking a

Thames waterman as ‘help.’ We set him, at first, for our strokesman,

but we soon had to make him row _bow_, for we could none of us stand

his gripping, arm-working style.

_BETTING ON HORSE RACES: OR, THE STATE OF THE ODDS._

There appears every day in the newspapers an account of the betting

on the principal forthcoming races. The betting on such races as the

Two Thousand Guineas, the Derby, and the Oaks, often begins more than

a year before the races are run; and during the interval, the odds

laid against the different horses engaged in them vary repeatedly, in

accordance with the reported progress of the animals in their training,

or with what is learned respecting the intentions of their owners. Many

who do not bet themselves, find an interest in watching the varying

fortunes of the horses which are held by the initiated to be leading

favourites, or to fall into the second rank, or merely to have an

outside chance of success. It is amusing to notice, too, how frequently

the final state of the odds is falsified by the event; how some ‘rank

outsider’ will run into the first place, while the leading favourites

are not even ‘placed.’

It is in reality a simple matter to understand the betting on races (or

contests of any kind), yet it is astonishing how seldom those who do

not actually bet upon races have any inkling of the meaning of those

mysterious columns which indicate the opinion of the betting world

respecting the probable results of approaching contests, equine or

otherwise.

Let us take a few simple cases of ‘odds,’ to begin with; and, having

mastered the elements of our subject, proceed to see how cases of

greater complexity are to be dealt with.

Suppose the newspapers inform us that the betting is 2 to 1 against

a certain horse for such and such a race, what inference are we to

deduce? To learn this let us conceive a case in which the _true_ odds

against a certain event are as 2 to 1. Suppose there are three balls

in a bag, one being white, the others black. Then, if we draw a ball

at random, it is clear that we are twice as likely to draw a black as

to draw a white ball. This is technically expressed by saying that

the odds are 2 to 1 _against_ drawing a white ball; or 2 to 1 _on_

(that is, in favour of) drawing a black ball. This being understood,

it follows that, when the odds are said to be 2 to 1 against a certain

horse, we are to infer that, in the opinion of those who have studied

the performance of the horse, and compared it with that of the other

horses engaged in the race, his chance of winning is equivalent to the

chance of drawing one particular ball out of a bag of three balls.

Observe how this result is obtained: the odds are 2 to 1, and the

chance of the horse is as that of drawing one ball out of a bag of

three—three being the sum of the two numbers 2 and 1. This is the

method followed in all such cases. Thus, if the odds against a horse

are 7 to 1, we infer that the _cognoscenti_ consider his chance equal

to that of drawing one particular ball out of a bag of _eight_.

A similar treatment applies when the odds are not given as so many to

_one_. Thus, if the odds against a horse are as 5 to 2, we infer that

the horse’s chance is equal to that of drawing a white ball out of a

bag containing five black and two white balls—or seven in all.

We must notice also that the number of balls may be increased to any

extent, provided the proportion between the total number and the

number of a specified colour remains unchanged. Thus, if the odds are

5 to 1 against a horse, his chance is assumed to be equivalent to that

of drawing _one_ white ball out of a bag containing six balls, only one

of which is white; _or_ to that of drawing a white ball out of a bag

containing sixty balls, of which ten are white-and so on. This is a

very important principle, as we shall now see.

Suppose there are two horses (amongst others) engaged in a race,

and that the odds are 2 to 1 against one, and 4 to 1 against the

other-what are the odds that one of the two horses will win the race?

This case will doubtless remind my readers of an amusing sketch by

Leech, called—if I remember rightly—‘Signs of the Commission.’ Three

or four undergraduates are at a ‘wine,’ discussing matters equine. One

propounds to his neighbour the following question: I say, Charley,

if the odds are 2 to 1 against _Rataplan_, and 4 to 1 against _Quick

March_, what’s the betting about the pair?’—‘Don’t know, I’m sure,’

replies Charley; ‘but I’ll give you 6 to 1 against them.’ The absurdity

of the reply is, of course, very obvious; we see at once that the odds

cannot be heavier against a pair of horses than against either singly.

Still, there are many who would not find it easy to give a correct

reply to the question. What has been said above, however, will enable

us at once to determine the just odds in this or any similar case.

Thus-the odds against one horse being 2 to 1, his chance of winning is

equal to that of drawing one white ball out of a bag of _three_, one

only of which is white. In like manner, the chance of the second horse

is equal to that of drawing one white ball out of a bag of _five_,

one only of which is white. Now we have to find a number which is a

multiple of both the numbers three and five. Fifteen is such a number.

The chance of the first horse, modified according to the principle

explained above, is equal to that of drawing a white ball out of a bag

of fifteen of which _five_ are white. In like manner, the chance of

the second is equal to that of drawing a white ball out of a bag of

fifteen of which _three_ are white. Therefore the chance that _one of

the two_ will win is equal to that of drawing a white ball out of a bag

of fifteen balls of which _eight_ (_five_ added to _three_) are white.

There remain _seven_ black balls, and therefore the odds are 8 to 7

_on_ the pair.

To impress the method of treating such cases on the mind of the reader,

let us take the betting about three horses—say 3 to 1, 7 to 2, and 9

to 1 _against_ the three horses respectively. Then their respective

chances are equal to the chance of drawing (1) one white ball out of

_four_, one only of which is white; (2) a white ball out of _nine_,

of which two only are white; and (3) one white ball out of _ten_, one

only of which is white. The least number which contains four, nine, and

ten is 180; and the above chances, modified according to the principle

explained above, become equal to the chance of drawing a white ball out

of a bag containing 180 balls, when 45, 40, and 18 (respectively) are

white. Therefore, the chance that one of the three will win is equal

to that of drawing a white ball out of a bag containing 180 balls, of

which 103 (the sum of 45, 40, and 18) are white. Therefore, the odds

are 103 to 77 _on_ the three.

One does not hear in practice of such odds as 103 to 77. But

betting-men (whether or not they apply just principles of computation

to such questions, is unknown to me) manage to run very near the truth.

For instance, in such a case as the above, the odds on the three would

probably be given as 4 to 3—that is, instead of 103 to 77 (or 412 to

308), the published odds would be equivalent to 412 to 309.

And here a certain nicety in betting has to be mentioned. In running

the eye down the list of odds, one will often meet such expressions as

10 to 1 against such a horse _offered_, or 10 to 1 _wanted_. Now, the

odds of 10 to 1 _taken_ may be understood to imply that the horse’s

chance is equivalent to that of drawing a certain ball out of a bag

of eleven. But if the odds are offered and not taken, we cannot infer

this. The offering of the odds implies that the horse’s chance is _not

better_ than that above mentioned, but the fact that they are not taken

implies that the horse’s chance is _not so good_. If no higher odds are

offered against the horse, we may infer that his chance is _very little

worse_ than that mentioned above. Similarly, if the odds of 10 to 1 are

_asked for_, we infer that the horse’s chance is _not worse_ than that

of drawing one ball out of eleven; if the odds are not obtained, we

infer that his chance is _better_; and if no lower odds are asked for,

we infer that his chance is _very little better_.

Thus, there might be _three_ horses (A, B, and C) against whom the

nominal odds were 10 to 1, and yet these horses might not be equally

good favourites, because the odds might not be taken, or might be asked

for in vain. We might accordingly find three such horses arranged thus:—

Odds.

A 10 to 1 (wanted).

B 10 to 1 (taken).

C 10 to 1 (offered).

Or these different stages might mark the upward or downward progress

of the same horse in the betting. In fact, there are yet more delicate

gradations, marked by such expressions respecting certain odds,

as—_offered freely_, _offered_, _offered and taken_ (meaning that some

offers only have been accepted), _taken_, _taken and wanted_, _wanted_,

and so on.

As an illustration of some of the principles I have been considering,

let us take from the day’s paper,[18] the state of the odds respecting

the ‘Two Thousand Guineas.’ It is presented in the following form:—

TWO THOUSAND GUINEAS.

7 to 2 against _Rosicrucian_ (off.).

6 to 1 against _Pace_ (off.; 7 to 1 w.).

10 to 1 against _Green Sleeve_ (off.).

100 to 7 against _Blue Gown_ (off.).

180 to 80 against Sir J. Hawley’s lot (t.).

This table is interpreted thus: bettors are willing to lay the same

odds against _Rosicrucian_ as would be the true mathematical odds

against drawing a white ball out of a bag containing two white and

seven black balls; but no one is willing to back the horse at this

rate; on the other hand, higher odds are not offered against him. Hence

it is presumable that his chance is somewhat less than that above

indicated. Again, bettors are willing to lay the same odds against

_Pace_ as might fairly be laid against drawing one white ball out of

a bag of seven, one only of which is white; but backers of the horse

consider that they ought to get the same odds as might be fairly laid

against drawing the white ball when an additional black ball had been

put into the bag. As respects _Green Sleeve_ and _Blue Gown_, bettors

are willing to lay the odds which there would be, respectively, against

drawing a white ball out of a bag containing—(1) eleven balls, one only

of which is white, and (2) one hundred and seven balls, seven only of

which are white. Now, the three horses, _Rosicrucian_, _Green Sleeve_,

and _Blue Gown_, all belong to Sir Joseph Hawley, so that the odds

about the three are referred to in the last statement of the list just

given. And since none of the offers against the three horses have been

taken, we may expect the odds actually taken about ‘Sir Joseph Hawley’s

lot’ to be more favourable than those obtained by summing up the three

former in the manner we have already examined. It will be found that

the resulting odds (offered) against Sir J. Hawley’s lot—estimated in

this way—should be, as nearly as possible, 132 to 80. We find, however,

that the odds _taken_ are 180 to 80. Hence, we learn that the offers

against some or all of the three horses are considerably short of what

backers require; or else that some person has been induced to offer far

heavier odds against Sir J. Hawley’s lot than are justified by the fair

odds against his horses, severally.

I have heard it asked why a horse is said to be a favourite, though the

odds may be against him. This is very easily explained. Let us take as

an illustration the case of a race in which four horses are engaged to

run. If all these horses had an equal chance of winning, it is very

clear that the case would correspond to that of a bag containing four

balls of different colours; since, in this case, we should have an

equal chance of drawing a ball of any assigned colour. Now, the odds

against drawing a particular ball would clearly be 3 to 1. This, then,

should be the betting against each of the three horses. If any one of

the horses has less odds offered against him, he is _a favourite_.

There may be more than one of the four horses thus distinguished; and,

in that case, the horse against which the least odds are offered is

_the first favourite_. Let us suppose there are two favourites, and

that the odds against the leading favourite are 3 to 2, those against

the other 2 to 1, and those against the best non-favourite 4 to 1; and

let us compare the chances of the four horses. I have not named any

odds against the fourth, because, if the odds against all the horses

but one are given, the just odds against that one are determinable,

as we shall see immediately. The chance of the leading favourite

corresponds to the chance of drawing a ball out of a bag in which are

three black and two white balls, _five_ in all; that of the next to

the chance of drawing a ball out of a bag in which are two black and

one white ball, _three_ in all; that of the third, to the chance of

drawing a ball out of a bag in which are four black balls and one white

one, _five_ in all. We take, then, the least number containing both

five and three—that is, _fifteen_; and then the number of white balls,

corresponding to the chances of the three horses, are respectively six,

five, and three, or fourteen in all; leaving only _one_ to represent

the chance of the fourth horse (against which the odds are therefore

14 to 1). Hence the chances of the four horses are respectively as the

numbers _six_, _five_, _three_ and _one_.

I have spoken above of the published odds. The statements made in the

daily papers commonly refer to wagers actually made, and therefore

the uninitiated might suppose that everyone who tried would be able

to obtain the same odds. This is not the case. The wagers which are

laid between practised betting-men afford very little indication of

the prices which would be forced (so to speak) upon an inexperienced

bettor. Book-makers—that is, men who make a series of bets upon

several or all of the horses engaged in a race—naturally seek to give

less favourable terms than the known chances of the different horses

engaged would suffice to warrant. As they cannot offer such terms to

the initiated, they offer them-and in general success—fully—to the

inexperienced.

It is often said that a man may so lay his wagers about a race as to

make sure of gaining money whichever horse wins the race. This is not

strictly the case. It is of course possible to make sure of winning if

the bettor can only get persons to lay or take the _odds he requires to

the amount he requires_. But this is precisely the problem which would

remain insoluble if all bettors were equally experienced.

Suppose, for instance, that there are three horses engaged in a race

with equal chances of success. It is readily shown that the odds are

2 to 1 against each. But if a bettor can get a person to take even

betting against the first horse (A), a second person to do the like

about the second horse (B), and a third to do the like about the third

horse (C), and if all these bets are made to the same amount—say

1000_l._—then, inasmuch as only one horse can win, the bettor loses

1000_l._ on that horse (say A), and gains the same sum on each of the

two horses B and C. Thus, on the whole, he gains 1000_l._, the sum laid

out against each horse.

If the layer of the odds had laid the true odds to the same amount

on each horse, he would neither have gained nor lost. Suppose, for

instance, that he laid 1000_l._ to 500_l._ against each horse, and A

won; then he would have to pay 1000_l._ to the backer of A, and to

receive 500_l._ from each of the backers of B and C. In like manner,

a person who had backed each horse to the same extent would neither

lose nor gain by the event. Nor would a backer or layer who had wagered

_different_ sums _necessarily_ gain or lose by the race; he would gain

or lose _according to the event_. This will at once be seen, on trial.

Light Science for Leisure Hours A series of familiar essays on scientific subjects, natural phenomena, &c. · 第 17 / 19 段