George Everest.

A series of letters : addressed to His Royal Highness the Duke of Sussex, as president of the Royal Society, remonstrating against the conduct of that learned body. online

. (page 5 of 13)
Online LibraryGeorge EverestA series of letters : addressed to His Royal Highness the Duke of Sussex, as president of the Royal Society, remonstrating against the conduct of that learned body. → online text (page 5 of 13)
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ment, be allowed; nothing short of the extreme uncompromising
rigour of registry and observation, which is the fundamental prin-
ciple of the Great Trigonometrical Survey of India, can in my hum-
ble opinion be tolerated for an instant ; and he who in the smallest
item has ever been implicated in, or can be reasonably suspected
of interpolating, unless he should make a full and unqualified
confession of his offence, and give satisfactory assurance that
he will sin in likewise no more, can never be admitted to participate
in such experiments.

That practice which many persons have, even without bad
intentions, of jumping at a conclusion which they think they
see most clearly the moral-certainty men, for example do, in
my humble opinion, more mischief in perpetuating error, than
years of painful toil can compensate ; for where are we to put the



50

limit, and how decree the relative values of two sets of conflicting
data, unless the particulars of each are circumstantially and
faithfully recorded? And by how much more is the difficulty of
the task imposed on unflinching accuracy enhanced by the re-
flection that, let the pains taken be what they may, their results
can only enter into a competition with others, obtained in a style
which never ought to have been relied on, and which none but
either the bold impostor or the well-meaning but illogical en-
thusiast, would have resorted to.

On this account, if my voice have any weight with the Honour-
able Court of Directors, I shall most strenuously recommend
them to adopt especial measures to close the entrance to any
superficial data. My opinion has always been, and I have made
no scruple of offering it when I could do so consistently with
the respect I owe to them, that experiments calculated to
advance any branch of science are worthy of their patronage ;
but at the same time, it is a sentiment which I have always
avowed, that experiments either incautiously made or negligently
recorded, are far worse than no experiments at all.

The question, then, becomes an exceedingly simple one, and
resolves itself into this : Whether, seeing that the rigour of atten-
tion and trustworthiness which alone make results worth seek-
ing cannot be obtained without a considerable outlay, it be
advisable to incur that outlay, or dispose of the cash balance
in one of the many ways more immediately advantageous to the
great population which Providence has decreed they shall rule ?
This, I submit to your Royal Highness, is a matter which those
can best decide who know most of the facts of the case ; and
though it is my persuasion that the Court would most thankfully
receive any suggestions on this or any other subject from able
men who were acquainted with its merits ; yet, when thirty-
eight learned Fellows of the Royal Society stalk into the arena,
and, without knowing or caring for details and particulars,
proceed in all the pomp and pride of learning to lay down the
law your Royal Highness must forgive me for saying so but



51

it forcibly calls to my mind the story of the man who proposed
to do all sorts of impossibilities somehow by a spring.

I will, with your Royal Highness's permission, next pass on
to the subject of Pendulum experiments, in reference to which
I have to observe that Col. Lambton's authority is not to be
quoted in advocacy of invariable pendulums uncompensated.

That able and admirable philosopher was very clear-sighted
and discerning ; and as to my certain knowledge no pendulum
of that class had ever reached him, he is in nowise responsible
for any application which learned gentlemen may think proper
to give to his writings in connexion with it.

It had long been a favourite scheme, which CoL Lambton
entertained to the last, to use his astronomical clock, (a very
valuable time-piece by Earnshaw, now the property of the
Honourable E. I. Company, which had a compensated gridiron
pendulum,) at all the stations of the Great Arc, retaining its
length invariable, and determining the increments of gravity by
those of time.

When Capt. Kater's experiments with the reciprocal pendu-
lum first became known to him, his admiration of the principle
and ingenuity of the inventor were expressed in unmeasured
terms ; and he certainly then had thoughts of combining this
new and attractive implement with his former scheme, with the
intention of determining the absolute length of the seconds pen-
dulum ; but though he was sufficiently communicative, I cannot
call to mind that he ever proposed to abandon his compensated
pendulum for one uncompensated, and which had the manifest
disadvantage of combining errors of its own generation with
those of the clock to which it was referred.

Col. Lambton had, moreover, not seen the paper which the
Astronomical Society did me the honour to publish in their Trans-
actions, on this subject, in 1829-30, for he was then lying peace-
ably in his grave, and I was in the origin, and at the time of his
death in 1823, one of those who had, as heedlessly as others,
been drawn into the vortex of general admiration of the bright



52

conception of one whom we claimed as belonging to our Great
Trigonometrical Survey, and whose fame we cherished with
kindred pride and affection.

Therefore I submit to your Royal Highness that it is not
correct to cite Col. Lambton in support of what is at all dubious;
and that the invariable pendulum is liable to this objection, I
proceed to show.

In the first place it is, I contend, impossible to ascertain the
correct temperature of a bar of metal by suspending thermome-
ters contiguous to it in the air; nor is it practicable to do so even
when, as in the case of our standard bars, cavities are hollowed
out to receive the bulbs. This was effectually decided by Capt.
Wilcox, Mr. James Prinsep, and myself, in 1832, at the Govern-
ment Mint, at Calcutta, in a series of experiments, wherein a
current of steam was made to pass longitudinally along the bar,
which was for that purpose enclosed in a double cylindrical case
of white iron ; for immediately after the vapour had filled the
case, the thermometers, lodged in the cavities before mentioned,
rose to the boiling point, whilst contact with the bar itself was
still, and, for some time after, endurable without pain by the
hand.

Eventually it was found that the only possible method of
obtaining experiments worth the trouble of making or recording,
was to fill up the cavities with the bulbs in them to the orifice
with fluid mercury, which, with a little expense of time, brought
the desired end to pass ; and ever since that period all compari-
sons of iron standards have been invariably made in my depart-
ment with the same precaution, a practice which I should have
extended to brass scales also, but for the impossibility of using
fluid mercury in contact with that metal, without injury to both.

Now, the same cause which acts as a barrier to the introduc-
tion of this indispensable precaution in the case of the brass
scales of my department, must operate in the instance of all the
invariable or reciprocal pendulums which I have ever seen ; and
as the impossibility of ascertaining the correct temperature, when



53

it is neglected, has been proved by trial, and is matter of
notoriety in India, therefore it is logical to conclude, that the
true increment of the bar from the variations of temperature
never has in any one instance been known or can be deter-
mined, unless indeed the construction of the apparatus be
vastly improved over that which was in prevalent use in 1830.

Of the very few persons whose acquaintance I courted when I
was last in England, Sir James Ivory was one. That celebrated
philosopher was a Professor at the Royal Military College at
Marlow at the time of my entering that institution as a Cadet ;
and independent of all other considerations this would of itself
have sufficed to draw me closer to him ; but when I recollected
that in the theoretical part of the very profession to the practice
of which I had devoted the best years of my life, he was a
leading writer, if not looked up to universally as the very leader
of our flock the chief priest and expounder of our oracles,
I felt it indeed a very proud honour to be allowed to plead this
former acquaintance as an excuse for intruding on his retire-
ment.

That Sir James has forgotten me is but too clear the absent
are proverbially liable to such wrongs but that a name for
which I have ever felt, and shall never cease to feel, the most
unfeigned reverence, should appear amongst the thirty-eight

Fellows :

" This was the most unkindest cut of all."

This, however, is straying from my subject, which was not
my intention, but the object of the digression is to introduce
other matters bearing on the question of the pendulum ; for
together with the failure of all remembrance of my unimportant
self, it may not be groundless to apprehend that the recollection
of all conversation with me may have vanished from the memory
of my estimable friend.

J am, however, of those who, whether it be for their good or
evil fortune, do not so easily relinquish impressions of incidents
of any kind, and am particularly retentive of such as are cal-



54

culated to flatter my self-love ; wherefore I may be taken as
evidence in stating some parts of the conversation at such
occasional interviews as bear upon the subject, because the
opinions of that celebrated mathematician first called my atten-
tion to certain facts which I have since habitually kept in view.

I well remember then, please your Royal Highness, that at
one of those interviews Sir James Ivory first taught me to expect
that though a pendulum may be compensated so as to show
time most equably for twenty-four hours, yet it does not follow
that this perfect compensation will be preserved through the
intermediate portions of that diurnal revolution.

Now, though I dare say that this is a fact which many
learned gentlemen may have often heard of before, yet, making-
such allowance as I am entitled to claim from the peculiar
mode of life which 1 have led from my youth upwards, unpre-
judiced men will not deem it matter of marvel that it should
have been new to me some ten years ago ; and as I have stored
it up in my mind, so now I have other facts which tend greatly
to corroborate the hypothesis, if not as I conceive fully to
confirm it in all instances, of what is called the gridiron com-
pensation.

The compensation-measuring bars which Col. Colby invented
for the Great Trigonometrical Survey of Ireland, are, as your
Royal Highness is doubtless aware, arranged on the same prin-
ciple as the gridiron pendulum, that is to say, a nodal point is
fixed on a tongue projecting at each extremity by means of the
relative increments of brass and iron ; wherefore admitting that
like causes produce like effects, we may expect that if the idea
suggested by Sir James be applicable to the latter, the result
which it involves will also be apparent in the former.

Hence then is derived a very easy and certain mode of testing
the truth of the hypothesis; for those bars are habitually com-
pared by a numerous course of successive trials with a ten feet
iron standard, both before and after employment in a measure-
ment; and the results, nearly three thousand in number, all tend



55

to corroborate the notion that it happens in practice precisely as
my philosophic friend had predicted.

The admirable course of patient trial and investigation which
that accomplished gentleman, Capt. Drummond, of the Royal
Engineers, made at the Tower in 1827-8, under the orders of
Col. Colby, may or may not lead to the same conclusion ; for
though I was present at part of these and examined their
recorded peculiarities, I cannot remember that I bestowed the
pains they merited to search for the existence of this principle
amongst them. The cause of my omitting to do so may per-
chance have been, that I participated in the infectious oscitancy
of Somerset House, or that I had too many other things to
occupy my time ; but whatever might have been the reason, it
would have made me very careful to withhold my signature from
an Address in which such a question could have been involved
in its remotest bearing.

But, have the thirty-eight learned Fellows examined the
details of that course of experiments with the caution they
deserve? And do they go to support or disprove the opinion
that I have above advanced? It is in vain to urge distaste for
such an investigation. If the inclination for the do Ice far niente
and a quiet life be so absolute and irresistible, let it be said so,
and no person can have a right to require or expect what he
would not take the trouble of doing himself; but then I submit
to your Royal Highness that the tone of dictature must be
abandoned by those who shelter themselves under such a pretext ;
for to retain both privileges of ease and authority is contrary to
the trite and homely proverb, of the cake which cannot be kept
and eaten too.

As to the facts which I have myself brought together on this
subject, I am quite aware that the primd facie objection against
the conclusion above advanced will be, that the bars were not
in the origin properly compensated by Mr. Simms, and I am
prepared to admit the truth of this to a limited extent ; for, taking
a long series of observations, the result certainly points to a small



56

increment from temperature, to the extent of T V to ^ of that of
hammered iron, thus showing that the compound bar is what
we term somewhat undercompensated, but this law certainly does
not prevail between individual observations ; and so far from
there being any primd facie traces of its existence, there is as
often a semblance of a decrement as of an increment of length,
consequent on an increase of temperature.

But to what purpose do I enter into this lengthy detail ? For
the information of learned gentlemen who will perhaps find it
necessary to ask what measuring bars I am alluding to ; gen-
tlemen who sit quietly in their easy chairs, before their comfort-
able firesides in the winter, or may gaze at will on the verdant
lovely meadows, golden corn fields, and majestic ocean which
surrounds the shores of adorable England, not to speak of the
interminable delights of civilized life which are perpetually open
to them: what can it signify to them, or why are they to take
the trouble to ascertain what goes on in India?

I freely admit this plea, and if I had been left to proceed with
my work in peace, and unmolested to the end, I should never
have intruded myself on your Royal Highness, but reserved such
discussions as this for the period when, my labours being com-
pleted, I could have given them in a body to the public, neither
courting notoriety nor shrinking from criticism, or in other words,

' * For my own part, I could be well content

To entertain the lag end of my life

With quiet hours ; for I do protest

I have not sought the day of this dislike."

This premature discussion has therefore manifestly been forced
on me, by the intrusion of the thirty-eight learned Fellows into
my quarters; and as they have all the learning and all the
leisure as well as numbers on their side, against one poor soldier,
the privilege cannot be denied to me of being prepared to parry
blows which the abundant generosity displayed by my adversaries
shows me they are fully equal to aim behind my back, or at any
part which I may leave exposed.



57

I placed at the disposal of all gentlemen who desired to inform
themselves respecting the magnificent instruments ordered by the
Court of Directors, the amplest opportunity of doing so in 1830.
For upwards of twenty days the apparatus of which I speak was
open for actual inspection in its working order, in the suburbs of
London, at a cost of no less than 130 to the Honourable Court
of Directors ; and let the learned gentlemen who have signed the
Address ask themselves how many of them condescended to avail
themselves of that occasion ?

Now whether Capt. Drummond's course of experiments exhibits
traces of partial discrepancy and total regularity analogous to
mine, I cannot say ; and as I have not heard that any other person
has decided in the negative, I shall for the present consider them
as neutral testimony on the point, which it will be manifest to
your Royal Highness that I could not do in silence, consistently
with a due regard to the priority in this respect of the Gene-
ral Trigonometrical Survey of Ireland, and with the high esteem
which I personally entertain for the urbanity and cordiality which
I have universally met with from all the members of that estab-
lishment.

If then this reasoning be admitted, there will evidently be a
new source of error arising from a reference of the pendulum of
experiment to a clock, whose real rate at the instant of compa-
rison differs from that which is assumed as derived from obser-
vations of transits ; and it is useless for learned gentlemen to get
angry or dogmatical, and unite in a body to condemn such a
notion, because I, who am absent, and wandering in savage
wildernesses, presume to advocate it ; for your Royal Highness
will see that it was once entertained by Sir James Ivory himself,
and that to his teaching I am originally indebted for it.

Amongst those of my countrymen with whom I became
acquainted when I was last in England, I will take the liberty to
mention Mr. Dent, who is now in partnership with Mr. Arnold of
Fleet-street, and was then rapidly rising into eminence as a maker
of chronometers. To Mr. Dent I have often communicated my
sentiments on the imperfection of the go-between pendulum,



58

which I can never look on but as trenching on the legitimate
rights of the clock pendulum, which needs no such interloping
appendage.

My opinion has always been that which Col. Lambton enter-
tained as the basis of his projected experiments, namely, to use the
clock pendulum itself without any array of tail pieces, and disks,
and immersions, and emersions, and telescopes ; all which, though
no doubt they display great ingenuity and contrivance, yet to my
unsophisticated judgment seem only calculated to complicate a
very simple subject which it is advisable to reduce to its lowest
terms.

It was Mr. Dent's opinion that a clock constructed on that
suspension would not perform well ; and though I should not, as
a general practice, cite the bare opinion of any person in proof of
any thing but its being his opinion, yet, where the giver is a
person eminently successful in the practice of the particular
business to which it relates, it furnishes a strong primd facie
argument in favour of its correctness.

Let us examine, please your Royal Highness, how far Mr.
Dent may be right in this conception, and how far he is borne out
by other facts. There is an impression on my mind that I have
somewhere read that a celebrated German philosopher actually
ascertained by examination with a microscope of sufficient power,
that at that point of the arc of vibration where the resolved part
of the rotatory force in the direction parallel to the horizon was
greatest, the knife-edge actually slided along the agate plate ;
and the further impression is, that I have conversed with Mr.
Francis Baily on that subject: but it is so long since I have given
any close attention to questions of this nature that I cannot
speak very decidedly as to the fact, which luckily is the less
necessary in the present instance because Mr. Baily is not of the
absent, and can correct me, if I am wrong in citing him.

My impressions, it may be said, go for nothing, and the intro-
duction of them in a discussion of this nature is not consistent
with sound logic ; all which would be indisputable, but for the



59

consideration that the Court of Directors have pronounced their
fiat, that as long as I stay in India they will look to me as their
only responsible adviser ; wherefore, as the advice which I shall
consider it my duty to give to my masters, in return for their
confidence, will be made up altogether of my impressions, it is
manifestly desirable that I should be converted, before the string
of reforms and innovations projected by the thirty-eight learned
Fellows can proceed, and this is luckily more easy in the present
instance than it seems; for, though certainly the declaration
might come more gracefully from any other quarter, yet I beg
your Royal Highness will do me the justice to believe that there
is hardly a person existing more open to conviction, or more
amenable to the laws of demonstration and sound clear reason,
than my humble self.

What has been above offered respecting the invariable pendu-
lum, will equally apply to the reciprocal pendulum ; but in the
latter there are manifestly other points also to be attended to. Now
it is shown in the paper to which I took the liberty to advert some
time back, which has never been confuted, because as I believe
it is not to be impugned, and which, though now to all seeming
thrown aside and neglected as trash and rubbish, originally met
with a cordial reception from the Astronomical Society, and
cannot therefore be so utterly undeserving of notice as the
silence of the thirty-eight learned Fellows would leave us to
believe ; in that paper it is shown that there is an imaginary line
joining the centres of suspension and gravity, in which the centre
of oscillation will also be found, which has hitherto been practi-
cally intangible ; and that if the knife-edge be inclined to this
line, an error sufficiently sensible in amount to vitiate all the
experiments for absolute length will infallibly be incurred. Now
supposing the knife-edge to have been originally set by the
square, quite perpendicular to the face of the bar, that does not
argue that it is also perpendicular to the physical line ; and even
supposing that it were, in spite of the infinity of chances to one,
to have been so nicely set by the maker, who shall decide that it



60

will remain so, amidst the perpetual variations arising from
changes of temperature and other causes ?

My friend the late Mr. Edward Troughton, I know, immedi-
ately after the publication of my paper devised a pendulum of a
cylindrical form, with two circular collars united to it, and sus-
pended by two supports of the knife-edge form, the cylinder itself
being constructed of three tubes drawn one within the other, all
which was very well no doubt, and, as I conceive, might perhaps
have furnished the means of determining two lines, which would
give the length of the pendulum at their points of intersection
with the physical line above alluded to. That pendulum was in
progress when I left England, and I did not stay to witness its
completion ; but I never thoroughly understood the details of how
the distance between the two lines in question, which are obvi-
ously nodal lines, each defined by the intersection of the surface
of its collar with the plane perpendicular to the physical line, or
true axis of the vibrating body, was to be subjected to measure-
ment by means of micrometers.

I have great reliance in the sound judgment and inventive
resources of Mr. Troughton, and therefore conclude it to be likely
that he had duly provided for all this ; but as I did not convince
myself by actual trial and inspection of the fact, and, except in
points of revealed religion, never put implicit faith in any man's
infallibility, therefore there is another unfortunate prepossession
of mine standing in the way, which will be likely to tint with its
unhallowed hue all the advice which I may have occasion to
offer to my masters.

Your Royal Highness will see therefore that it is not the
Court of Directors of the E. I. Company, but I who am to blame,
for the omission of pendulum experiments, for the implements are
actually at my disposal as far as material is concerned ; that is
to say, two invariable pendulums and two clocks constructed by
no less celebrated an artist than Mr. Jones, of Charing Cross,
perfect, I believe, in all parts of their apparatus, and exactly like



61

those used by Captain Sabine, are at my command, and have
been since 1830, and all that since that time has been wanted is
the personel to put them into action.

Here is a frank avowal at least, and when the Court are called
on peremptorily to take in hand a work for which they naturally
conceive that they have already made all the provision which
rests with them, it becomes me to step forward and make the
controversy my own.

Much and anxiously as I desire to see the day when experi-


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Online LibraryGeorge EverestA series of letters : addressed to His Royal Highness the Duke of Sussex, as president of the Royal Society, remonstrating against the conduct of that learned body. → online text (page 5 of 13)