the neighbouring vessels. But since it seems probable, that the minute arteries are more affected by distension than the veins, there is reason in general to expect a more speedy and efficacious relief in inflammations, from opening an Arteriotomy. artery than a vein: this operation, however, can seldom be performed without material inconvenience; but it is proba bly for a similar reason, that greater benefit is often experienced from withdrawing a small portion of blood by means morrhage. of cupping or of leeches, than a much larger quantity by Cupping and venesection, since both the former modes of bleeding tend leeches. to relieve the arteries, as immediately as the veins, from that distension, which appears to constitute the most essential characteristic of inflammation. In a case of hemorrhage Use of toxfrom one of the sinuses of the brain, a very judicious phy- glove in he. sician lately prescribed the digitalis: if the effect of this medicine tends principally to diminish the action of the heart, as is commonly supposed, it was more likely to be injurious than beneficial, since a venous plethora must be increased by the inactivity of the heart; but if the digitalis diminishes the general tension of the arteries, in a greater proportion than it affects the motion of the heart, it may possibly be advantageous in venous hemorrhages. We have, however, no sufficient authority for believing, that it has any such effect on the arterial system in general. Muscular Although the arguments, which I have advanced, appear powers of the to me sufficient to prove, that, in the ordinary state of the arteries have circulation, the muscular powers of the arteries have little effect on very the ordinary little effect in propelling the blood, yet I neither expect circulation. nor desire, that the prevailing opinion should at once be universally abandoned. I wish, however, to protest once more against a hasty rejection of my theory, from a superficial consideration of cases, like that which has been related by Dr. Clarke; and to observe again, that the objections, which I have adduced, against the operation of the muscular powers of the arteries in the ordinary circulation, not being applicable to these cases, they are by no means weakened by any inferences which can be drawn from them. IV. Defcription of a Scarificator on a new Principle. By Mr. New scarifica tor. Cupping evidently advan tageous. IF SIR, F the annexed description of a Scarificator, which I have found upon trial to be extremely efficient, should appear worthy of insertion in your Journal, I have taken the liberty of transmitting it to you for that purpose. I am, Sir, Park Street, Bristol, Your most obedient humble Servant, The advantages resulting from a local evacuation of blood by cupping, in a variety of complaints, being fully established, it would, I presume, be a waste of time elaborately to descant on the merits of such depletion, as forming The operation a high and important remedy in the curative art. It must sometimes however be admitted, that the operative means, which have tedious, pain- been hitherto employed for this purpose, are not only too ful, and in effectual, often tedious and painful in their applications, but very frequently extremely ineffectual in the event. Such being the acknowledged fact, and regarding it as very improbable, that the difficulty of obtaining blood could depend on a want of manual dexterity in the operator, when the scarificator usually employed had passed through the hands of so many able practitioners, it seemed natural to conclude, that probably from the want of success ought rather to be attributed to some fault in the construction of the instrument itself. Impressed with these ideas, and having taken up an opinion, that the failure of the scarificator now in use might be attributed to the manner in which the incisions are made; and supposing, that simple punctures would more certainly enter Alteration of the depths intended; I flatter myself, that, by altering the its principle. principle on which the instrument used to act, I have produced one, which will effect all the purposes required with more facility to the operator, and less pain to the patient. defects of the instrument. Without tual. Without any intention then extravagantly to extol the This instru properties of a new instrument, or unnecessarily to depre- ment effecciate the merits of an old one, I take the liberty of recommending one to my medical brethren for their approbation, which I have found to answer in my hands much better than any other that I have yet been able to procure. That the instrument here recommended will invariably produce the wished for effect, I am sanguine enough to believe; at the same time that I, by no means, mean to assert it is not still capable of farther improvement. A draught taken by Mr. Mac Donald, a friend and pupil of mine, is subjoined, sufficiently explanatory as I hope of the fabric of the instrument, which may be purchased of Mr. Winter, Cutler, Bridge Street. It is my intention, at no very distant period, to offer a few observations on the formation and number of the lancets, so as more immediately to adapt them to particular parts of the body. Explanation of the Plate. Plate IV, fig. 1, 2, and 3. a a nut, by means of which, The scarifica acting on the screw b, the plates c and d, holding the lan- tor described. cets, are drawn upwards, till the catch e falls into the notch at f. The nut is then unscrewed; and, by pushing in the knob g, the catch is withdrawn, and the worm spring h immediately forces down the lancets. i, a spring acting on the catch e, to force it into the notch. k, a box, which, by means of the screws 11, regulates at will the exposure of the lancets, and in consequence the depth of the incisions. The figures are on a scale of half an inch to an inch. 1 Theory of capillary ac tion imperfect. The pheno mena may be estimated from the figure of V. On the Theory of Capillary Attraction. By THOMAS SIR, To Mr. NICHOLSON. NOTWITHSTANDING the attention, that has lately been paid to the phenomena arising from capillary action, the theory appears to be still in a very imperfect state. have endeavoured, in what follows, to throw some light on that part, which is most defective. The insertion of it, in your valuable Journal, will speedily bring my ideas before competent judges, And much oblige, Sir, Your most obedient Servant, Papcastle, near Cockermouth, July 22d, 1810. There are two ways of treating the subject of capillary action; first, the measure of the other phenomena may be estimated from the figure of the surface, which is a simultathe surface, of neous effect with the height of the fluid: or, secondly, in a more natural manner, from the forces themselves which support the fluid. from the forces. Mistake of If, with Mr. La Place and Dr. Young, the first method Mr. la Place. be made use of, we must take care not to mistake an effect for the cause, as the former of these authors appears at first to have done. But, even if we do not fall into this errour, a theory, which stops here, must appear, I think, to any one, to be exceedingly defective. Let the hydrostatic principle, of the perpendicularity of the force to the surface, be used to explain what relates to the figure of that surface: * It is very remarkable, that Dr. Young, in his observations on Mr. la Place's theory, should not have noticed the chief circumstance in which it differs from all others: viz. "Que l'eau s'élève, dans un tube capillaire, par l'effet de la concavité de sa surface intérieure." Sur l'Action capillaire p. 60. Whether Dr. Young himself be of this opinion, I do not very clearly perceive. but, but, by all means, let us have a view of the mechanism by which the whole column is supported. method. Mr. La Place, probably from considering the matter in Errour in his this light, gave the world his second method; which appears sccond to be as erroneous in falsely explaining the true*, as the first had been in assigning a wrong cause. My own intention, at present, is to show what part of a Object of the capillary tube keeps a fluid elevated; and the precise man- author. ner, in which it causes this elevation: or, in other words, to supersede this second method of Mr. La Place, and all similar theories, by one more conformable to truth. Abat. The remarkable experiment of Abat, which Mr. La Place Experiment of seems to have thought one of the best proofs of his first theory, will be very easily explained here on quite different principles. We shall also see what is the limit of the height of the fluid in that experiment, which no one I believe has yet shown. the fluid for I suppose, with Mr. La Place, and other writers on the Attraction of subject, that the attractions of the particles of the fluid for itself and for itself, and of the tube for the fluid, extend only to insensi- the tube differs ble distances; that they follow the same law of the distances; sity. only in inteaand only differ by their intensity at the same distance. Prop. Let ABCDEF (fig. 4) be the section, through the Proposition. axis, of a circular tube, every where of equal diameter, bent into a rectangular form, and standing in a vertical plane. Let the part A B C D, of the tube, be formed of matter, the intensity of attraction of which for the fluid within it is represented by r, while that of the other part CDEF is. The excess of the mass of fluid in the leg A B over that in the leg E F is as (2r-2r) x diameter of the tube. tion. Let e n m n be a slender canal of fluid, extending from Demonstrathe surface in one leg to that in the other, and parallel to the side of the tube, as well as every where at the same distance from it. It is, in the first place, evident that this * The balancing force of the tube. canal |