The first step in the use of every instrument, is to find the limits within which its employer can measure the SAME OBJECT UNDER THE SAME CIRc.u.mSTANCES. It is only from a knowledge of this, that he can have confidence in his measures of the SAME OBJECT UNDER DIFFERENT CIRc.u.mSTANCES, and after that, of DIFFERENT OBJECTS UNDER DIFFERENT CIRc.u.mSTANCES.
These principles are applicable to almost all instruments. If a person is desirous of ascertaining heights by a mountain barometer, let him begin by adjusting the instrument in his own study; and having made the upper contact, let him write down the reading of the vernier, and then let him derange the UPPER adjustment ONLY, re-adjust, and repeat the reading. When he is satisfied about the limits within which he can make that adjustment, let him do the same repeatedly with the lower; but let him not, until he knows his own errors in reading and adjusting, p.r.o.nounce upon those of the instrument. In the case of a barometer, he must also be a.s.sured, that the temperature of the mercury does not change during the interval.
A friend once brought to me a beautifully constructed piece of mechanism, for marking minute portions of time; the three-hundredth parts of a second were indicated by it. It was a kind of watch, with a pin for stopping one of the hands. I proposed that we should each endeavour to stop it twenty times in succession, at the same point. We were both equally unpractised, and our first endeavours showed that we could not be confident of the twentieth part of a second. In fact, both the time occupied in causing the extremities of the fingers to obey the volition, as well as the time employed in compressing the flesh before the fingers acted on the stop, appeared to influence the accuracy of our observations. From some few experiments I made, I thought I perceived that the rapidity of the transmission of the effects of the will, depended on the state of fatigue or health of the body. If any one were to make experiments on this subject, it might be interesting, to compare the rapidity of the transmission of volition in different persons, with the time occupied in obliterating an impression made on one of the senses of the same persons. For example, by having a mechanism to make a piece of ignited charcoal revolve with different degrees of velocity, some persons will perceive a continuous circle of light before others, whose retina does not retain so long impressions that are made upon it.
SECTION 3. ON THE FRAUDS OF OBSERVERS.
Scientific inquiries are more exposed than most others to the inroads of pretenders; and I feel that I shall deserve the thanks of all who really value truth, by stating some of the methods of deceiving practised by unworthy claimants for its honours, whilst the mere circ.u.mstance of their arts being known may deter future offenders.
There are several species of impositions that have been practised in science, which are but little known, except to the initiated, and which it may perhaps be possible to render quite intelligible to ordinary understandings. These may be cla.s.sed under the heads of hoaxing, forging, tr.i.m.m.i.n.g, and cooking.
OF HOAXING. This, perhaps, will be better explained by an example. In the year 1788, M. Gioeni, a knight of Malta, published at Naples an account of a new family of Testacea, of which he described, with great minuteness, one species, the specific name of which has been taken from its habitat, and the generic he took from his own family, calling it Gioenia Sicula. It consisted of two rounded triangular valves, united by the body of the animal to a smaller valve in front. He gave figures of the animal, and of its parts; described its structure, its mode of advancing along the sand, the figure of the tract it left, and estimated the velocity of its course at about two-thirds of an inch per minute. He then described the structure of the sh.e.l.l, which he treated with nitric acid, and found it approach nearer to the nature of bone than any other sh.e.l.l.
The editors of the ENCYCLOPEDIE METHODIQUE, have copied this description, and have given figures of the Gioenia Sicula. The fact, however, is, that no such animal exists, but that the knight of Malta, finding on the Sicilian sh.o.r.es the three internal bones of one of the species of Bulla, of which some are found on the south-western coast of England, [Bulla lignaria] described and figured these bones most accurately, and drew the whole of the rest of the description from the stores of his own imagination.
Such frauds are far from justifiable; the only excuse which has been made for them is, when they have been practised on scientific academies which had reached the period of dotage. It should however be remembered, that the productions of nature are so various, that mere strangeness is very far from sufficient to render doubtful the existence of any creature for which there is evidence; [The number of vertebrae in the neck of the plesiosaurus is a strange but ascertained fact] and that, unless the memoir itself involves principles so contradictory, as to outweigh the evidence of a single witness, [The kind of contradiction which is here alluded to, is that which arises from well ascertained final causes; for instance, the ruminating stomach of the hoofed animals, is in no case combined with the claw-shaped form of the extremities, frequent in many of the carniverous animals, and necessary to some of them for the purpose of seizing their prey] it can only be regarded as a deception, without the accompaniment of wit.
FORGING differs from hoaxing, inasmuch as in the latter the deceit is intended to last for a time, and then be discovered, to the ridicule of those who have credited it; whereas the forger is one who, wishing to acquire a reputation for science, records observations which he has never made. This is sometimes accomplished in astronomical observations by calculating the time and circ.u.mstances of the phenomenon from tables.
The observations of the second comet of 1784, which was only seen by the Chevalier D"Angos, were long suspected to be a forgery, and were at length proved to be so by the calculations and reasonings of Encke. The pretended observations did not accord amongst each other in giving any possible orbit. But M. Encke detected an orbit, belonging to some of the observations, from which he found that all the rest might be almost precisely deduced, provided a mistake of a unity in the index of the logarithm of the radius vector were supposed to have been made in all the rest of the calculations. ZACH. CORR. ASTRON. Tom. IV. p. 456.
Fortunately instances of the occurrence of forging are rare.
Tr.i.m.m.i.n.g consists in clipping off little bits here and there from those observations which differ most in excess from the mean, and in sticking them on to those which are too small; a species of "equitable adjustment," as a radical would term it, which cannot be admitted in science.
This fraud is not perhaps so injurious (except to the character of the trimmer) as cooking, which the next paragraph will teach, The reason of this is, that the AVERAGE given by the observations of the trimmer is the same, whether they are trimmed or untrimmed. His object is to gain a reputation for extreme accuracy in making observations; but from respect for truth, or from a prudent foresight, he does not distort the position of the fact he gets from nature, and it is usually difficult to detect him. He has more sense or less adventure than the Cook.
OF COOKING. This is an art of various forms, the object of which is to give to ordinary observations the appearance and character of those of the highest degree of accuracy.
One of its numerous processes is to make mult.i.tudes of observations, and out of these to select those only which agree, or very nearly agree.
If a hundred observations are made, the cook must be very unlucky if he cannot pick out fifteen or twenty which will do for serving up.
Another approved receipt, when the observations to be used will not come within the limit of accuracy, which it has been resolved they shall possess, is to calculate them by two different formulae. The difference in the constants employed in those formulae has sometimes a most happy effect in promoting unanimity amongst discordant measures. If still greater accuracy is required, three or more formulae can be used.
It must be admitted that this receipt is in some instances rather hazardous: but in cases where the positions of stars, as given in different catalogues, occur, or different tables of specific gravities, specific heats, &c. &c., it may safely be employed. As no catalogue contains all stars, the computer must have recourse to several; and if he is obliged to use his judgment in the selection, it would be cruel to deny him any little advantage which might result from it. It may, however, be necessary to guard against one mistake into which persons might fall.
If an observer calculate particular stars from a catalogue which makes them accord precisely with the rest of his results, whereas, had they been computed from other catalogues the difference would have been considerable, it is very unfair to accuse him of COOKING; for--those catalogues may have been notoriously inaccurate; or--they may have been superseded by others more recent, or made with better instruments; or--the observer may have been totally ignorant of their existence.
It sometimes happens that the constant quant.i.ties in formulae given by the highest authorities, although they differ amongst themselves, yet they will not suit the materials. This is precisely the point in which the skill of the artist is shown; and an accomplished cook will carry himself triumphantly through it, provided happily some mean value of such constants will fit his observations. He will discuss the relative merits of formulae he has just knowledge enough to use; and, with admirable candour a.s.signing their proper share of applause to Bessel, to Gauss, and to Laplace, he will take THAT mean value of the constant used by three such philosophers, which will make his own observations accord to a miracle.
There are some few reflections which I would venture to suggest to those who cook, although they may perhaps not receive the attention which, in my opinion, they deserve, from not coming from the pen of an adept.
In the first place, it must require much time to try different formulae. In the next place it may happen that, in the progress of human knowledge, more correct formula: may be discovered, and constants may be determined with far greater precision. Or it may be found that some physical circ.u.mstance influences the results, (although unsuspected at the time) the measure of which circ.u.mstance may perhaps be recovered from other contemporary registers of facts. [Imagine, by way of example, the state of the barometer or thermometer.] Or if the selection of observations has been made with the view of its agreeing precisely with the latest determination, there is some little danger that the average of the whole may differ from that of the chosen ones, owing to some law of nature, dependent on the interval between the two sets, which law some future philosopher may discover, and thus the very best observations may have been thrown aside.
In all these, and in numerous other cases, it would most probably happen that the cook would procure a temporary reputation for unrivalled accuracy at the expense of his permanent fame. It might also have the effect of rendering even all his crude observations of no value; for that part of the scientific world whose opinion is of most weight, is generally so unreasonable, as to neglect altogether the observations of those in whom they have, on any occasion, discovered traces of the artist. In fact, the character of an observer, as of a woman, if doubted is destroyed.
The manner in which facts apparently lost are restored to light, even after considerable intervals of time, is sometimes very unexpected, and a few examples may not be without their use. The thermometers employed by the philosophers who composed the Academia Del Cimento, have been lost; and as they did not use the two fixed points of freezing and boiling water, the results of a great ma.s.s of observations have remained useless from our ignorance of the value of a degree on their instrument.
M. Libri, of Florence, proposed to regain this knowledge by comparing their registers of the temperature of the human body and of that of some warm springs in Tuscany, which have preserved their heat uniform during a century, as well as of other things similarly circ.u.mstanced.
Another ill.u.s.tration was pointed out to me by M. Gazzeri, the Professor of Chemistry at Florence. A few years ago an important suit in one of the legal courts of Tuscany depended on ascertaining whether a certain word had been erased by some chemical process from a deed then before the court. The party who insisted that an erasure had been made, availed themselves of the knowledge of M. Gazzeri, who, concluding that those who committed the fraud would be satisfied by the disappearance of the colouring matter of the ink, suspected (either from some colourless matter remaining in the letters, or perhaps from the agency of the solvent having weakened the fabric of the paper itself beneath the supposed letters) that the effect of the slow application of heat would be to render some difference of texture or of applied substance evident, by some variety in the shade of colour which heat in such circ.u.mstances might be expected to produce. Permission having been given to try the experiment, on the application of heat the important word reappeared, to the great satisfaction of the court.
CHAPTER VI. SUGGESTIONS FOR THE ADVANCEMENT OF SCIENCE IN ENGLAND.
SECTION 1. OF THE NECESSITY THAT MEMBERS OF THE ROYAL SOCIETY SHOULD EXPRESS THEIR OPINIONS.
One of the causes which has contributed to the success of the PARTY, is to be found in the great reluctance with which many of those whose names added l.u.s.tre to the Society expressed their opinions, and the little firmness with which they maintained their objections. How many times have those whose activity was additionally stimulated by their interest, proposed measures which a few words might have checked; whilst the names of those whose culpable silence thus permitted the project to be matured, were immediately afterwards cited by their grateful coadjutors, as having sanctioned that which in their hearts they knew to be a job.
Even in the few cases which have pa.s.sed the limits of such forbearance, when the subject has been debated in the Council, more than one, more than two instances are known, where subsequent circ.u.mstances have occurred, which proved, with the most irresistible moral evidence, that members have spoken on one side of the question, and have voted on the contrary.
This reluctance to oppose that which is disapproved, has been too extensively and too fatally prevalent for the interests of the Royal Society. It may partly be attributed to that reserved and retiring disposition, which frequently marks the man of real knowledge, as strongly as an officious interference and flippant manner do the charlatan, or the trader in science. Some portion of it is due to that improper deference which was long paid to every dictum of the President, and much of it to that natural indisposition to take trouble on any point in which a man"s own interest is not immediately concerned. It is to be hoped, for the credit of that learned body, that no antic.i.p.ation of the next feast of St. Andrew ever influenced the taciturnity of their disposition. [It may be necessary to inform those who are not members of the Royal Society, that this is the day on which those Fellows who choose, meet at Somerset House, to register the names of the Council and Officers the President has been pleased to appoint for the ensuing year; and who afterwards dine together, for the purpose of praising each other over wine, which, until within these few years, was PAID for out of the FUNDS of the Society. This abuse was attacked by an enterprising reformer, and of course defended by the coterie. It was, however, given up as too bad. The public may form some idea of the feeling which prevails in the Council, when they are informed that this practice was defended by one of the officers of the Society, on the ground that, if abolished, THE a.s.sISTANT SECRETARY WOULD LOSE HIS PERCENTAGE ON THE TAVERN BILLS.]
SECTION 2. OF BIENNIAL PRESIDENTS.
The days in which the Royal Society can have much influence in science seem long past; nor does it appear a matter of great importance who conduct its mismanaged affairs. Perpetual Presidents have been tried until the Society has become disgusted with dictators. If any reform should be attempted, it might perhaps be deserving consideration whether the practice of several of the younger inst.i.tutions might not be worthy imitation, and the office of President be continued only during two sessions. There may be some inconveniences attending this arrangement; but the advantages are conspicuous, both in the Astronomical and Geological Societies. Each President is ambitious of rendering the period of his reign remarkable for some improvement in the Society over which he presides; and the sacrifice of time which is made by the officers of those Societies, would become impossible if it were required to be continued for a much longer period. Another circ.u.mstance of considerable importance is, that the personal character of the President is less impressed on the Society; and, supposing any injudicious alterations to be made, it is much less difficult to correct them.
SECTION 3. OF THE INFLUENCE OF THE COLLEGES OF PHYSICIANS AND SURGEONS IN THE ROYAL SOCIETY.
The honour of belonging to the Royal Society is much sought after by medical men, as contributing to the success of their professional efforts, and two consequences result from it. In the first place, the pages of the Transactions of the Royal Society occasionally contain medical papers of very moderate merit; and, in the second, the preponderance of the medical interest introduces into the Society some of the jealousies of that profession. On the other hand, medicine is intimately connected with many sciences, and its professors are usually too much occupied in their practice to exert themselves, except upon great occasions.
SECTION 4. OF THE INFLUENCE OF THE ROYAL INSt.i.tUTION ON THE ROYAL SOCIETY.
The Royal Inst.i.tution was founded for the cultivation of the more popular and elementary branches of scientific knowledge, and has risen, partly from the splendid discoveries of Davy, and partly from the decline of the Royal Society, to a more prominent station than it would otherwise have occupied in the science of England. Its general effects in diffusing knowledge among the more educated cla.s.ses of the metropolis, have been, and continue to be, valuable. Its influence, however, in the government of the Royal Society, is by no means attended with similar advantages, and has justly been viewed with considerable jealousy by many of the Fellows of that body. It may be stated, without disparagement to the Royal Inst.i.tution, that the scientific qualifications necessary for its officers, however respectable, are not quite of that high order which ought to be required for those of the Royal Society, if the latter body were in a state of vigour.
The Royal Inst.i.tution interest has always been sufficient to appoint one of the Secretaries of the Royal Society; and at the present moment they have appointed two. In a short time, unless some effectual check is put to this, we shall find them nominating the President and the rest of the officers. It is certainly not consistent with the dignity of the Royal Society thus to allow its offices to be given away as the rewards of services rendered to other inst.i.tutions. The only effectual way to put a stop to this increasing interest would be, to declare that no manager or officer of the Royal Inst.i.tution should ever, at the same time, hold office in the Royal Society.
The use the Members of the Royal Inst.i.tution endeavour to make of their power in the Council of the Royal Society, is exemplified in the minutes of the Council of March 11, 1830, which may be consulted with advantage by those who doubt.
SECTION 5. OF THE TRANSACTIONS OF THE ROYAL SOCIETY.
The Transactions of the Royal Society, unlike those of most foreign academies, contain nothing relating to the history of the Society. The volumes contain merely those papers communicated to the Society in the preceding year which the Council have selected for printing, a meteorological register, and a notice of the award of the annual medals, without any list of the Council and officers of the Society, by whom that selection and that award have been made.