thankfulness, at the happy result of his bold attempt, to which the Prince warmly and gratefully insisted that I had mainly contributed.

It was from his own lips that I received the details of his most wonderful escape.

No sooner was the Prince safe on the British soil than he wrote letters to Sir Robert Peel, Lord Aberdeen, and the French Ambassador.

To the latter (Le Comte de St. Aulaire) the Prince wrote the following letter:

London: May 28, 1846. Sir, I come frankly to declare to the man who was the friend of my mother, that in escaping from my prison I never intended to repeat against the French Government the attempts that have proved so disastrous to myself. My only object was to see my old father again.

Before making up my mind to have recourse to the last extremity-flight-I exhausted every means of entreaty to be allowed to go to Florence, giving at the same time every possible guarantee compatible with my honour. All my solicitations having met with refusal, I have done what the Duc de Guise and the Duc de Nemours did under Henry the Fourth in similar circumstances.

I beg you will make known to the French Government my peaceful intentions, and I hope that this declaration, utterly spontaneous, will have the effect of shortening the time of captivity of those of my friends who are still in prison.

N. L. BONAPARTE.

The narrative of the escape would remain incomplete if I did not relate what passed at Ham after the departure of the Prince.

Dr. Conneau, whose devotedness to the Prince had filled his whole life, had undertaken the difficult task of making it appear, as long as possible, that it had not taken place.

The very first thing he did was to shut the door of the bedroom, next to the sitting-room, where he had a great fire made, despite the heat of the day, alleging the indisposition of the Prince. eight o'clock A.M., breakfast being

At

ready, the doctor ordered it to be laid in his own bedroom, the more so as General Montholon was also ill in bed. He added that the Prince had been taking medicine, and to convince everybody that what he stated was true, he manufactured a mixture of coffee and roasted bread with addition of a quantity of nitric acid, which being boiled for a few minutes, filled the rooms with such a sick-room odour as to give the warders the conviction there was no mistake about it!

The Governor soon came to inquire for the Prince.

was

rather better, and was taking a The doctor said that he little rest on the sofa in the sittingroom.

All went right until seven o'clock in the evening, when the Governor came again, and on the doctor telling him the Prince was better, the Governor said, 'As the Prince is better I must see him; I must The simulated speak to him.'

form

of a man had been adroitly arranged in the bed, having what seemed to be his head turned towards the wall. The doctor called the Prince. No answer. Turning to the Governor, he said, "The Prince is fast asleep.' The Governor did not appear quite satisfied with this prolonged pantomime. 'I will take a seat in the next room,' said he, 'till his sleep is over. By the bye, how is it that Thélin is not back yet? The diligence has arrived and Thélin not here. Strange, very strange! Let us see.'

The doctor rushed into the room, and coming out again, said, 'No, no, he is still sleeping;' but the Governor could stand this anxious suspense no longer. He entered the room, and pulling the bed clothes right off, discovered the trick!

'Good God!' said he, the Prince is gone!'

The reader will easily imagine his state of bewildered distraction.

In the course of the next day the order came to arrest the Governor, the doctor, and all the warders. Doctor Conneau was handcuffed and sent to Peronne to be tried, and sentenced to three months' imprisonment. Charles Thélin was sentenced by default to six months' of the same penalty.

The first thing the Prince did was to fulfil the sacred duty which had induced him to undertake such a daring adventure. The illness of his father making rapid progress, the Prince had no time to lose if he wished to bid his father a last farewell. He applied for a passport to the Austrian Ambassador in

London, who was at the same time the accredited representative of the Grand Duke of Tuscany. The passport was refused, on the plea that it was a matter concerning the French Government. The Grand Duke of Tuscany was solicited by various members of the family to grant the request, but he answered that he could not tolerate the presence of the Prince twenty-four hours in the Duchy, owing to the French influence opposing it. The Belgian Government was still harsher, as it inscribed the name of the Prince among those who were condemned to extradition by the clauses of the treaties. LONDON: March 8, 1879.

IN

N his Preliminary Discourse on the Study of Natural Philosophy, Sir John Herschel remarks upon the importance of examining those phenomena of nature which are not wholly explicable in terms of any well-established theory. Instances of such residual phenomena, as Sir John Herschel terms them, are given in the discourse.

Newton's theory of comets, viz. that these bodies obey the law of gravitation while revolving in oblique orbits round the sun, appeared to account for the facts which had been noticed concerning the comet of Halley; but the period calculated for Encke's comet, on this hypothesis, was found to be rather longer than the actual, observed period, and, moreover, the duration of the observed period showed a small but regular diminution. Hence, Newton's theory, taken alone, was not sufficient to account for the facts. But inasmuch as Newton's Law of Gravitation rested upon a sure and well-established foundation, the fact observed concerning Encke's comet could not be regarded as disproving the law; hence these facts were to be explained by tracing them to the action of some agent either of known or of, as yet, unknown nature.

The regularly diminishing period of Encke's comet remained a residual phenomenon, not contradicting the law of gravitation, but awaiting full explanation.

A residual phenomenon is, then, a phenomenon which is not fully explained by any established theory; but at the same time it is not a phenomenon which is absolutely contradictory to any such theory, for if this were the case, the theory in question must perforce be abandoned.

Advances are made in natural science by a judicious use of hypotheses. Facts are accurately observed, or are gained by exact experiment, and are compared with facts; inferences are drawn, and are compared with other inferences, until a good working hypothesis is attained. From this hypothesis deductions are made which must necessarily prove true if the hypothesis be correct; the truth or falsity of the alleged facts is tested by an appeal to Nature; and so wider hypotheses are gained, each in turn being tested and tried by an appeal to facts, until, finally, that generalisation is reached which includes in its expression so many and so varied phenomena that to it is given the name of a 'law of Nature.'

But notwithstanding the sure and tried foundations upon which each law of nature rests, phenomena ever and anon become apparent which refuse to be completely explained by any of these laws. Upon more careful examination, it may be found that such phenomena have been erroneously observed, and they may be brought under the application of a known law, acting, perhaps, in a peculiar and even unprecedented manner. In such cases the phenomena cease to be residual phenomena.

But, on the other hand, some of the observed phenomena may resist every attempt made to explain them; they may refuse to retire from the list of established facts, and at the same time refuse to find their full explanation in terms of any wellestablished law. But while so doing, these phenomena may also not be opposed to the law; they may not be contradictory to, but simply not wholly explainable by, any known law of nature.

Instances of the valuable results which have been obtained by the exact investigation of residual phenomena are numerous in every branch of natural science. One of the most striking is furnished by Newton's investigation of the atmospheric velocity of sound.

Newton showed that the velocity of sound in air might be calculated from certain theoretical considerations; a rough measurement of the actual velocity gave him a number differing very considerably from that which his theory required. Later and more exact experiments failed to explain the discrepancy, but in 1816 Laplace gave an explanation of the seemingly exceptional phenomenon, which not only sustained the theory of Newton, but also paved the way to the modern doctrine of the equivalency of heat and mechanical work. In the residual phenomenon which was left unexplained by Newton lay the germ of one of the greatest advances made by science in recent years.

Another striking instance of the value of residual phenomena is to be found in the history of Chemical Science.

From his experiments upon combustion, Lavoisier concluded that the peculiar properties of acids are due to the presence of the element oxygen in these bodies. But an

undoubtedly acid substance was known (muriatic acid) from which no oxygen could be obtained. Here was a residual phenomenon: a phenomenon not absolutely contradictory of the law, that that group of bodies called acids is characterised by the presence of oxygen, but certainly a phenomenon demanding accurate investigation. Closer examination might have shown that the acid supposed to contain no oxygen was not really free from that element, or it might have led to the adoption of a higher generalisation concerning the nature of the group 'acids,' or, lastly, it might

have necessitated an entire alteration in the terms of Lavoisier's socalled law.

Chemists, however, for many years contented themselves with asserting that, as Lavoisier had pronounced oxygen to be the acidifying principle, and as muriatic acid was undoubtedly a true acid, this body must contain oxygen. But Sir Humphry Davy showed that an accurate examination of the residual phenomenon presented by muriatic acid, led to a more extended and more exact knowledge of the nature of acids, and necessitated a change in the prevalent views concerning these bodies. The views of Lavoisier were found to express a truth, but not the whole truth; fresh incitement was given to research, and fresh advances were quickly made in the knowledge of groups of compound bodies.

But there is another way in which the investigation of residual phenomena may aid, and has largely aided, the advance of scientific knowledge.

Phenomena, regarded as residual, have not unfrequently been shown to be completely explicable in terms of a known law; and thus fresh light has been thrown upon the modifying influence exerted on the action of the law by the conditions under which the law acts.

The orbit of Lexell's comet was accurately determined, nevertheless, the comet failed to appear at the proper time. Here, surely, was a phenomenon which could not be explained by the law of gravitation alone: hypotheses, plausible and probable in themselves, were broached to account for the apparently exceptional phenomenon. But subsequent investigation showed that that appearance of the comet, from observations of which the orbit had been calculated, was due to the disturbing influence of one of the members of the solar system (probably of Jupiter) whereby the comet had been dragged within the

limits of our vision, but that this visit to earthly spheres was altogether abnormal: the phenomenon presented by the visit of the comet was entirely explicable in terms of the law of gravitation.

What could be more opposed to our ordinary notions concerning the effects of heat than the fact that water should be frozen in a redhot vessel? But this phenomenon, apparently inexplicable in terms of any known law, upon exact investigation finds demonstrable explanation without recourse being had to the action of an unknown agent. The experiment is carried out by pouring liquid sulphur dioxide-a liquid which boils at a temperature lower than that of the freezing point of water-into a red-hot platinum crucible, immediately adding a little water, and quickly turning out the ice which is produced.

Experiment shows that when a liquid is suddenly brought into contact with a highly heated smooth surface, vapour is evolved which surrounds the mass of liquid as it were with a screen through which the heat, radiated from the hot surface underneath, passes but slowly; the liquid thus rests upon a cushion of its own vapour, and does not = touch the hot surface beneath. The temperature of a mass of liquid in this (spheroidal) condition is lower than that at which the liquid boils. Now, as liquid sulphur dioxide boils at a temperature lower than that at which water freezes, and as immediately the liquid touches the heated platinum crucible it is partially vaporised, and the residual liquid is then floated, so to speak, upon the stratum of gas so produced, it follows that so long as this condition is maintained, the liquid contents of the crucible are at a very low temperature, hence the temperature of the water coming into contact with this cold liquid is greatly reduced, and the water is frozen.

Exact investigation of this phe

nomenon, therefore, adds much to our knowledge of the laws which govern the vaporisation of liquids, and shows us these laws at work under peculiar conditions, while at the same time it brings the apparently exceptional phenomenon under the domain of a known law. Once more, the examination of residual phenomena may be, and has often been, of immense service to science, in freeing naturalists from. the tyranny of an established theory which has for long been regarded as of necessity affording a full explanation of the entire series of facts. to which it is applied.

The tyranny of orthodoxy is not unknown in science. The overthrow of that tyranny is one result of the investigation of residual phenomena.

During the greater part of the eighteenth century the theory of Phlogiston was all prevalent in chemistry. According to this theory, when a body burns, it gives out a something called Phlogiston, the escape of this mystical something being the cause of the phenomena which attend the combustion.

This theory accounted in a fairly satisfactory manner for the greater number of the observed facts. One little fact, however, was scarcely explicable by the Phlogistic theory. So far as rough measurement went,. the weight of the burnt body appeared to be greater than that of the body previous to combustion. This residual fact was long overlooked, but the genius of Lavoisier forbade him to pass over so important a circumstance. By repeated and exact experiment, Lavoisier established the correctness of the residual phenomenon, and he showed that the phenomenon was inexplicable in terms of the commonly accepted theory.

Modern research has taught us that the fact firmly established by Lavoisier is not absolutely contradictory of a modified Phlogistic