of compressed air, in the case of the letters F and V, between the lips, in that of the TH, between the tongue and upper teeth, and in that of the letters S and Z between the teeth. In the stammering enunciation of the letters of the third class, there is frequently a state of laborious respiration. In all these cases, then, it is plain that the larynx is open; any considerable effort applied to the parts concerned in the articulation of the first class of letters, the least noise,-the least escape of air, alike demonstrate this fact. In the natural, and in the stammering articulation, there is the same total or partial interruption of the expiration, at the same parts, not of the larynx, but of the proper organs of articulation, only in different degrees. Let the larynx be really closed, which may be done after a little trial, and it will immediately be discovered that stammering is, in fact, impossible; the effort made by the force of the expired air against the parts of the mouth called into action in the articulation of the first class of letters,-all escape of air,—all noise, become totally interrupted.

I have just attentively watched the attempts of a stammerer to articulate the various letters.

In the effort to pronounce the first class of letters, especially the letter T, still more if two T's come together, as in the words THAT TREE, the face became flushed even from interrupted expiration; yet there was, at every repetition of the effort, a noise audible in the larynx, proving that this part was unclosed.

In pronouncing the letters of the second class, a repeated hissing noise was distinctly produced by the flow of the compressed air, in one case, (F, V,) between the under lip and upper teeth; in the second, (TH,) between the tongue and upper teeth; and in the third, (S, Z,) between the teeth.

In attempting the articulation of some of the letters of the third and fourth classes, and of some of the vowels, the breath was sometimes lost, as it were, in a full and exhausting expiration, altogether peculiar.

All these results prove that the larynx is not closed in stammering, and indeed that its closure and stammering are totally incompatible with each other. When expiration is interrupted,

it is by the co-operation, the coadaptation, of parts anterior to the larynx; it is, in a word, not an interruption in the organ of voice, but in that of speech. The paralysis of the laryngal muscles could not, therefore, effect the good which Dr. Arnott ingeniously supposes.

But would no evil really result from this paralysis of the muscles of the larynx? Would the loss of the faculty of closing the larynx" really 'be of no moment'? On the contrary, the accurate closure of the larynx, not by the epiglottis, but by means of its own muscles, is essential to the act of deglutition. This is demonstratively proved by M. Magendie, in his interesting memoir, Sur l'usage de l'Epiglotte dans la Deglutition.' The fact is further proved by cases of actual paralysis of the laryngal muscles occurring in the human body, and by the effects of inflammation and contraction, and of ulceration, of the internal parts of the larynx, in inducing defective deglutition.

The rule proposed by Dr. Arnott for remedying stammering, does not attach itself exclusively to the view which that gentleman has taken of the subject. On the contrary, the very same rule was proposed by myself, in the paper to which allusion has already been made, in the following words :- Let a stammerer observe this rule: always to speak in a continuous or flowing manner, avoiding carefully all positive interruption in his speech; and if he cannot effect his purpose in this way, let him even half sing what he says, until he shall, by long habit and effort, have overcome his impediment; then let him gradually, as he may be able, resume the more usual mode of speaking, by interrupted enunciation. I am persuaded, that this is the principal means employed by those gentlemen who have undertaken to correct impediments in the speech, and it is, undoubtedly, the most rational. In addition to this rule, let the stammerer endeavour to speak in as calm and soft a tone as possible; for in this way the muscles of speech will be called least forcibly into action, and that action will be least liable to those violent checks or interruptions, in which stammering appears to consist. It would, of course, be irrelevant to the object of this essay, to allude to those other principles

connected with stammering, such as nervousness, of which it would be necessary to treat, in an essay written expressly on this important and interesting subject.'

I am persuaded that I need not apologize to Dr. Arnott for this free and plain discussion of his views relative to stammering, our mutual object being the discovery and establishment of truth.

OBSERVATIONS ON MR. RENNIE'S PAPER ON THE PECULIAR HABITS OF CLEANLINESS

IN SOME ANIMALS.

BY WILLIAM AINSWORTH, Esq.

IN the first number of the Journal of the Royal Institution, I observe a paper on the cleanliness of animals by Mr. Rennie, in which it is advanced upon the authority of Wilson, the author of the American Ornithology, that the serrated structure of the claw of the goat-sucker is employed as a comb to rid the plumage of vermin-an erroneous opinion as to its use having been held by Swainson, White, &c.

It is a fact, not generally known, that the claws of most birds are used for similar purposes; and thus birds which have short legs, as the swift, are most infested by insects. The expedients which birds characterized by short feet-the waders which, from the inflexible nature of their legs, and the geese tribe, from the opposition to scratching, offered by the membrane extending between the toes, are put to, in order to get rid of their vermin, are well deserving of attention, as illustrating the ingenuity of animals, and the curious provisions made by nature for their cleanliness. When birds, by accident or imprisonment, are deprived of the natural means of ridding. themselves of vermin, they often fall victims to these attacks. Walking one day along the shore of Holy-Island, off the coast of Northumberland, I disturbed an ash-coloured sanderling (Calidris Islandica, Step.), which flew heedlessly, and as if injured. On shooting the bird, I found that it was covered with vermin, more especially about the head; so much so, that the poor thing must have fallen a victim to their tormenting ravages on further examination, I found that it had lost

one of its legs, so that it was from its incapability to rid itself of these insects that their extraordinary increase was to be attributed. A circumstance of a similar kind also came under my notice connected with a swallow's nest. After the young birds had been hatched, and had attained a certain size, a change was made in the arrangement of the window, which frightened the parents: from that time they continued to feed their offspring, but never entered the nest; and I soon observed that the young ones were sick, and one by one they perished. I then took the nest down, and found it crowded with acari, which were of a very great size compared with that of the bird itself. I could only attribute this fatal increase of vermin to the old birds having been prevented cleaning out the abode of their family.

Poultry which run about in stony or paved yards, wear away the points of their claws by friction and digging, which renders them unfit to penetrate their coating of feathers; they are, therefore, more covered with vermin, and in consequence more sickly than fowls from the country.

ON THE AURORA BOREALIS OF THE 7TH OF JANUARY, 1831. By S. H. CHRISTIE, Esq., M.A., F.R.S., &c.

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[To the Editor of Q. J. of Science, &c.]

Woolwich Common, 7th January, 1831.

OU will not, I think, be sorry to have some account of the appearance of the very beautiful aurora of this evening, in this neighbourhood, where, perhaps, I had a better opportunity of viewing it than you might have in town. I was not, however, under very favourable circumstances for making remarks upon it, as I was, for a considerable part of the time during which it appeared, travelling, being outside of our coach. I first observed it at 5h. 30m., being then on Blackheath, about half a mile S.W. from the observatory. At this time I observed a strong white light, resembling the tail of a comet, but denser, like a light cloud illuminated by the moon, proceeding from near Betelguex in the east towards Aldebaran.

It very quickly spread in this direction towards the south, and was soon joined by a similar band of light proceeding from the west, the whole now forming a strongly-marked arch, about 5o in breadth, pretty well defined on the upper side, but not so well on the lower. The highest point of the arch passed over the planet Mars, about 45° above the horizon. Towards the west the arch was lost in what appeared to be the London smoke, about 10° above the horizon; and towards the east, about the same portion was lost in haze; or rather it appeared to proceed from the smoky fog at this height on the west, and the haze on the east. The whole had the white appearance of a thin cloud illuminated by the moon. The brightest parts were to the S.E. and S.W. This arch faded gradually away, but was visible for nearly a quarter of an hour. Before it had disappeared, I observed a strong light in the N.E. (at this time I was about three-quarters of a mile S.E. from the observatory) of a brilliant rose colour. This increased rapidly in brilliancy, and sent coruscations up to the zenith. Very shortly afterwards the whole of the northern horizon became illuminated, and brilliant coruscations shot from every part towards the zenith. Some of these were very thin and well defined; but were not much tinged with red, excepting towards the N.E. and N.W. At the same time large detached masses of light, resembling floating clouds, were seen on the southern side from east to west; and similar ones, though not so strongly enlightened, appeared towards the north. These, towards the north, after a short time, assumed the appearance of an irregular inverted arch, the lowest point being, as near as I could judge, in the magnetic north, and brilliant coruscations proceeded rapidly from every part, some being slightly tinged with red. Shortly after six o'clock, when I arrived here, these gradually diminished in brightness; and at half past six, little more could be observed than a general light diffused over the northern side of the heavens. At 7h. 30m. I observed a distinct arch of light towards the north, the centre of the arch being very nearly in the magnetic north, and its highest point about 25° or 30° above the horizon. The eastern and western ends of this arch, like that which first appeared towards the south, were not visible near to the horizon.