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PLEURAL EFFUSION AND ITS TREATMENT.
593 bear the burden. Judging by the examination of school children for diseases of the eye, which is already in force, no
attempt will be made to ascertain whether the parents are in If the a position to pay, however inadequately, for advice. scheme is extended to include diseases of the skin, general debility, &c., general medical practitioners must inevitably suffer severely.
I have been led to trouble you with this letter more on account of the false analogy which is likely to be made between special diseases, such as diseases of the eye and other complaints. It has already been pointed out in your columns that the work now done by the County Council oculists might equally well be done by teachers after a short course of instruction, and you have advocated that the oculists should correct the refractions which at present they are occupied in discovering. I am in complete agreement with this policy which would relieve hospital clinics of uninteresting drudgery and would entail no hardship It is a very different matter, upon general practitioners. however, to hand over to the County Council the treatment of other minor complaints and more serious diseases affecting school children, for this would be in the highest degree detrimental to hospital clinics and general practitioners, as well as entailing enormous expense. More than ever at the present time questions continually arise which demand coordinated action on the part of the medical staffs of the London hospitals. Lack of coi5rdination in matters such as that under consideration is likely to lead to schemes which fall short of the best which can be In this manner the praiseworthy aims of the devised. County Council and of the hospitals, which are alike working for the alleviation of suffering, are liable to be frustrated. The lay control of the London hospitals is in some considerable degree coordinated by the Council of King Edward’s Hospital Fund. I would suggest that a standing committee composed of representatives of the medical staffs of the London hospitals be formed to which matters of mutual interest might be referred with a view to coordinated action. The Central Hospital Council does not exactly meet the requirements of the case. I am, Sir, yours faithfully, J. HERBERT PARSONS. Wimpole-street, W., Feb. 15th, 1908.
particularly
DEVELOPMENT OF NODULES IN SUTURE SCARS AFTER OPERATIONS FOR THE REMOVAL OF CANCER. To the Editor of THE LANCET.
as to how the latter condition occurred appears to me to be a perfectly rational one, and I may add that a similar condition has come under my own observation. The fact that no nodules appeared in the scars of the superficial stitches leads one to infer that there were no free cancer cells at the time of operation and that the infection in the tracks of I the deeper sutures came from the abdomen. Cancer cell& escaped where the sutures pierced the peritoneum, and finding their way along the tracks there they became lodged, and probably the tissues damaged by the suture proved Where the themselves a ready site for implantation. abdomen is closed by a single row of "through and through " sutures the infection will sometimes spread along the whole suture track, and, in fact, in cases of tubercular disease of the peritoneum, tubercular infection spreads in a similar way along the suture. Doubtless Mr. Mansell Moullin’s suggestion explains the occurrence of these phenomena. On the other hand, his explanation of the occurrence of cancer nodules in suture scars, after operations for mammary cancer, is a totally different one. He suggests that cancer cells may be present in the tissues, and that the irritation of the sutures may cause these cells to take on greater activity at the points of irritation, hence the subsequent development of suture scar nodules. Though I recognise the possibility of this, yet I very much doubt that it is a frequent occurrence. It is a recognised fact that the peripheral spread of mammary cancer is almost entirely by the lymphatics, Therefore, if cancer cells are present in the tissues of the flaps it almost necessarily follows that infected lymphatics must have been divided at the time of operation, thus allowing the escape of cancer cells. From my experience these latter would very readily manifest themselves by setting up cancerous infection along the line of incision, if they did not even cause widespread infection of the whole wound. It is not so much that cancer cells are already present and that they take on activity owing to diminished resistance of the tissues as the result of irritation of the sutures, which is mainly the cause of suture scar " recurrence." Our own faulty technique is more frequently responsible. It permits the escape of free cancer cells, which readily implant themselves in whatever part of the wound they may come to rest, or to whatever part of it they are carried by the This explains surgeon, whether by suture or otherwise. many of the cases of suture scar infection, but there are others, and Mr. Mansell Moullin’s interesting case is one of these, where the suture does not actually carry infection ; but, on the other hand, it encourages or permits of ready I am, Sir, yours faithfully, implantation. CHARLES RYALL. Harley-street, W., Feb. llth, 1908.
explanation
SIR,-In THE LANCET of Feb. 1st Mr. C. W. Mansell Moullin, in a paper on the above subject, draws attention to cancer nodules occurring in the cicatrices caused by the sutures used in closing the abdomen in a case of cancer of PLEURAL EFFUSION AND ITS the pylorus which had been under his care. In referring to a TREATMENT. publication of mine in THE LANCET of Nov. 9th, 1907, in which somewhat similar cases were reported, he considers To the Editor of THE LANCET. that the appearance of nodules in his case suggests that SIR,-In my letter in THE LANCET of to-day, p. 521, col. 1, the mode of conveying cancer infection to the suture second line, "not elastic"should be "non-elastic" ; p. 522, tracks is not so simple as is generally believed. My col. twentieth line, " abstract quantity " should be 2, paper referred to the danger of cancer infection and "abstract quality." I would not have troubled about these its importance in relation to the question of "recurrence." trivial mistakes only I am dealing with two soi-disant philoI tried to demonstrate that the cancer cell is infective, and and I don’t wish even a printer’s error to creep into, sophers if set it be therefore free at the time of operation it is liable letter. I am, Sir, yours faithfully, to be implanted by the surgeon or else implant itself in some my JAMES BARR. Liverpool, Feb. 15th, 1908. the wound and thus rise to a fresh cancerous of give part I outbreak. The cases of suture star nodules quoted were To the Editor of THE LANCET. given as illustrations of how readily cancer cell implantation ’ may occur and also as some of the possible ways in which SIR,-You have been so generous with your space that I forbear to reply categorically to Sir James Barr’s last letter, implantation may be brought about. In the course of my experience I have come across a great the more so that a detailed reply would involve much many varieties of infection of the suture tracks :in some repetition and probably weary your readers. That Sir James the infection was limited to the superficial and in others to and I differ profoundly on the subject of pulmonary physics the deeper layers of the skin ; and, again, it manifested is becoming more and more obvious. Sir James now asserts itself as a nodule deeply in the tissues directly in the that the tautness of the lungs does not exert traction, that course of the sutures ; and I have also seen it occurring the pulmonary tissue is not relaxed at the end of a full as infection of the entire track of the suture ; nevertheless, respiration, that the fibroid apices of the lungs in fibroid it is far from belief that these cancer I I recurrences " were phthisis do not drag in the chest walls, and that, no matter all due to infection having been carried there on the needle how many of the pulmonary vessels are destroyed in this or sutures. In Mr. Mansell Moullin’s case two sets of sutures disease, if "taut lungs constantly maintained a negative were used in closing the wound, one of stout catgut, interintrathoracic pressure there could be no obstruction to the rupted, passing through all the layers of the abdominal wall systemic venous circulation." (Not even if all the pulmonary except the skin; the other of finer catgut, continuous, capillaries were reduced to a single one !) In my opinion all through the skin only. Practically all the suture points of these contentions are wrong. the former series were infected; none of the latter. His It seems to me, Sir, that the time has now come for the -
JAMES
594 retire and consider the verdict. I have stated my I could and am content to let it stand as it is-unamended and unqualified. I am, Sir, yours faithfully, HARRY CAMPBELL. Wimpole-street, Feb. 16th, 1908.
jury to
case as
simply as
To the Editor of THE LANCET. SIR,-I have carefully read and re-read the correspondence between Sir James Barr and Dr. Harry Campbell, and the
conclusion I have come to is that it has been greatly confused through a lack of knowledge and precision on the part of the former in discussing the physical problems involved, and on the part of the latter through the use of unnecessarily complicated phraseology. The employment of the terms " tautness " and " traction by Dr. Campbell is peculiarly unfortunate, as they,’at "
least it appears
so much the word " tension." Tension is a state of strain, or the act of straining, and is a term perfectly well understood. Pulmonary tautness is a pulmonary state of strain, or tension. Pulmonary traction is a pulmonary act of straining, or tension. The word "tension" implies both the condition and the act. The tension of a wire means that it is tight and that it pulls ; and it would be absurd to worry over its tautness and traction, as both are stated or implied when one speaks of its tension. Dr. Campbell says I "fail to make the necessary disI purposely tinction between tautness and elasticity." avoided discussing the subject, but the distinction is obvious. There can be tension or tautness in a wire far beyond what its elasticity can produce or resist, or there may be tension or tautness less than what its elasticity can produce or resist, in which case the force of elastic recoil or tautness are equal. There can be tension or tautness in a fibroid lung as I am quite at one with Dr. well as in an elastic one. Campbell in distinguishing between tautness (or tension) and elasticity : where I differ is when he says that the negative I intrapleural pressure when the thorax and respiratory muscles are at rest " is due to the tautness of the pulmonary ’, tissue pure and simple, and that the factor of elasticity, or elastic recoil, has nothing to do with it." Dr. Campbell, like so many people who discover a truth, fails to see its limita-
more
so
to me, could both have been
easily expressed by
tions.
Suppose there be a large pneumothorax ; the lung recedes far from the body wall and rests contracted. Gradually, by vital processes, the air is absorbed, and as the chest walls cannot fall in so readily as the lungs can stretch, the latter expand and presently again fill the thorax. What stretched the lungs? Dr. Campbell says " the stretched condition of the pulmonary tissue is effected by the inspiratory muscles." I maintain that the cell action, or other vital processes which actively absorbed the air from the pleural sac, lowered the pressure in it and cleared the space for the lung to expand into, primarily caused its expansion, by decreasing the opposition to the action of the intrapulmonary air pressure. Likewise though at birth the lung is stretched by the thoracic expansion, the lung at, say, ten years of age is another lung, and I can conceive of no other way in which the new elastic tissue has kept on the stretch than by supposing it has been laid down on the stretch, or has contracted afterwards. In this way the elastic tension producing the intrapleural negative pressure, when the thorax and respiratory muscles are at rest, is generated within the lung, and in time would pull the visceral and parietal pleuræ apart if their lining cells would allow air or liquid to accumulate there and permit their separation. When the inspiratory muscles expand the thorax beyond the position of rest then it is that they obviously operate in lowering the intrapleural pressure. In addition to his employment of the words "tautness" and "traction " Dr. Campbell also seems to me unfortunate in his use of the word "suction." He does not use it as indicating a force decreasing the resistance to another force, as Sir James Barr rightly contends he should, but as though it were the force directly producing the effects observed. These are minor matters; the great principle for which Dr. Campbell has so earnestly contended-viz., the much overlooked importance of the action of the inspiratory movements in their effects within the chest, and the nature of these effects-he has done much to elucidate and establish, and I personally feel much indebted to him for what I have learned at his hands. In regard to Sir James Barr’s criticisms, it seems to me, after his letter of Jan. 25th, there is little to
be gained by discussing physics with him. gives from the 11 century Dictionary" a "
He there
definition A body is of elastic in which it is stated, perfectly elastic when it has the property of resisting a given deformation equally ......," and he remarks: "The Campbell physicist says it is a mere property of a certain form of matter, by which it has the power of recovering its original form after being stretched, but I prefer the other authority who says that it also signifies a resistance to stretching or other deformation." Now the other authority which Sir James Barr quotes and prefers does not say it "signifies a resistance to stretching or other deformation." The words are, it has the property of resisting," and it is this idea of a property which Dr. Campbell and I want Sir James Barr to admit. Surely it would be better if Sir James would " prefer" the definition of elasticity given by the authority from which he quotes, the " Century Dictionary," rather than his own misquotation from that authority. Sir James Barr shortly after proceeds in his letter to what he calls "prick the bubble " blown by Dr. Campbell, and he compares the uses of a "non-elastic chain" and what he terms "a hawser made of highly elastic hemp." He says : " The elastic rope offers resistance to being stretched and when the tug of the ship ceases the elasticity gradually pulls the vessel back to its former position." Sir James Barr should know that a hawser is made on the twist, and it stretches, not because hemp is what he styles "highly elastic," but because the component fibres and twists straighten out under tension, taking a direction more along the length of the rope than before and less across it, while at the same time mutually compressing one another. If Sir James twists a piece of string he will see that it shortens and will then lengthen when pulled upon more than before. The recoil in the hawser is due to the recovery of the parts from mutual compression and has nothing at all to do with elasticity in hemp. Moreover, if Sir James considers hemp highly elastic, why does he immediately speak of " nonelastic fibroid lungs "? By what mental process does he make hemp highly elastic and fibroid lungs non-elastic ? Later in his letter Sir James tells how he was selected by the Home Office to " devise a method of estimating the elasticity of any rope," and he modestly says, "Idid not retire to my study and work out the coefficient of elasticity, and what should, but probably would not, happen. I determined the vis viva or energy which I considered necessary, and then under a strain of a given number of foot pounds I determined the stretch, and I had no difficulty in devising a method of measuring the length of unstretched rope which would allow of a given energy." Fancy speaking of the length of unstretched rope which would allow of a given energy! Energy is the "capacity for doing work," and is measured by the amount of work a body having energy can be made to do. What capacity for doing work is inherent in a piece of unstretched rope. Would it allow of boiling a kettle or climbing a hill ? It would have been far better if Sir James Barr had retired to his disparaged study and learned the elements of physics as taught before hastily experimenting. He might then have started with ideas of energy, elasticity, &o., which were physically precise. Sir James Barr’s criticism in your last issue of my letter of Jan. 25th calls for little comment. He seems to hold me responsible for the consequences of the physical definition He says : "Let us see how his definition of elasticity. works out." It is nothing to me how my definition works out and what confusion or sadness it produces in the mind of Sir James. If he discusses physics as a physicist he must take the consequences, however they work out; if as the man in the street " he may call hemp highly elastic, rubber more elastic, and gas most elastic, but he must pose in future as the "man in the street " and not as a physicist. I will leave my last letter and Sir James Barr’s criticism of it to the impartial judgment of your readers as this communication is already too long, but I hope more particularly that Dr. Campbell’s suggestive views may have the attention which I think they deserve. I am, Sir, yours faithfully, D. W. SAMWAYS. Mentone, Feb. 17th, 1908. The various this *** parties to correspondence have had ample space in which to expound their views, and none of them can complain of the undue vigour of their opponents’ language, for none of them has failed to reply with equal vigour. As they cannot all have the last word we supply it. This interesting discussion must now cease.-ED. L. ’’
"
"
I
"
attempt will be made to ascertain whether the parents are in If the a position to pay, however inadequately, for advice. scheme is extended to include diseases of the skin, general debility, &c., general medical practitioners must inevitably suffer severely.
I have been led to trouble you with this letter more on account of the false analogy which is likely to be made between special diseases, such as diseases of the eye and other complaints. It has already been pointed out in your columns that the work now done by the County Council oculists might equally well be done by teachers after a short course of instruction, and you have advocated that the oculists should correct the refractions which at present they are occupied in discovering. I am in complete agreement with this policy which would relieve hospital clinics of uninteresting drudgery and would entail no hardship It is a very different matter, upon general practitioners. however, to hand over to the County Council the treatment of other minor complaints and more serious diseases affecting school children, for this would be in the highest degree detrimental to hospital clinics and general practitioners, as well as entailing enormous expense. More than ever at the present time questions continually arise which demand coordinated action on the part of the medical staffs of the London hospitals. Lack of coi5rdination in matters such as that under consideration is likely to lead to schemes which fall short of the best which can be In this manner the praiseworthy aims of the devised. County Council and of the hospitals, which are alike working for the alleviation of suffering, are liable to be frustrated. The lay control of the London hospitals is in some considerable degree coordinated by the Council of King Edward’s Hospital Fund. I would suggest that a standing committee composed of representatives of the medical staffs of the London hospitals be formed to which matters of mutual interest might be referred with a view to coordinated action. The Central Hospital Council does not exactly meet the requirements of the case. I am, Sir, yours faithfully, J. HERBERT PARSONS. Wimpole-street, W., Feb. 15th, 1908.
particularly
DEVELOPMENT OF NODULES IN SUTURE SCARS AFTER OPERATIONS FOR THE REMOVAL OF CANCER. To the Editor of THE LANCET.
as to how the latter condition occurred appears to me to be a perfectly rational one, and I may add that a similar condition has come under my own observation. The fact that no nodules appeared in the scars of the superficial stitches leads one to infer that there were no free cancer cells at the time of operation and that the infection in the tracks of I the deeper sutures came from the abdomen. Cancer cell& escaped where the sutures pierced the peritoneum, and finding their way along the tracks there they became lodged, and probably the tissues damaged by the suture proved Where the themselves a ready site for implantation. abdomen is closed by a single row of "through and through " sutures the infection will sometimes spread along the whole suture track, and, in fact, in cases of tubercular disease of the peritoneum, tubercular infection spreads in a similar way along the suture. Doubtless Mr. Mansell Moullin’s suggestion explains the occurrence of these phenomena. On the other hand, his explanation of the occurrence of cancer nodules in suture scars, after operations for mammary cancer, is a totally different one. He suggests that cancer cells may be present in the tissues, and that the irritation of the sutures may cause these cells to take on greater activity at the points of irritation, hence the subsequent development of suture scar nodules. Though I recognise the possibility of this, yet I very much doubt that it is a frequent occurrence. It is a recognised fact that the peripheral spread of mammary cancer is almost entirely by the lymphatics, Therefore, if cancer cells are present in the tissues of the flaps it almost necessarily follows that infected lymphatics must have been divided at the time of operation, thus allowing the escape of cancer cells. From my experience these latter would very readily manifest themselves by setting up cancerous infection along the line of incision, if they did not even cause widespread infection of the whole wound. It is not so much that cancer cells are already present and that they take on activity owing to diminished resistance of the tissues as the result of irritation of the sutures, which is mainly the cause of suture scar " recurrence." Our own faulty technique is more frequently responsible. It permits the escape of free cancer cells, which readily implant themselves in whatever part of the wound they may come to rest, or to whatever part of it they are carried by the This explains surgeon, whether by suture or otherwise. many of the cases of suture scar infection, but there are others, and Mr. Mansell Moullin’s interesting case is one of these, where the suture does not actually carry infection ; but, on the other hand, it encourages or permits of ready I am, Sir, yours faithfully, implantation. CHARLES RYALL. Harley-street, W., Feb. llth, 1908.
explanation
SIR,-In THE LANCET of Feb. 1st Mr. C. W. Mansell Moullin, in a paper on the above subject, draws attention to cancer nodules occurring in the cicatrices caused by the sutures used in closing the abdomen in a case of cancer of PLEURAL EFFUSION AND ITS the pylorus which had been under his care. In referring to a TREATMENT. publication of mine in THE LANCET of Nov. 9th, 1907, in which somewhat similar cases were reported, he considers To the Editor of THE LANCET. that the appearance of nodules in his case suggests that SIR,-In my letter in THE LANCET of to-day, p. 521, col. 1, the mode of conveying cancer infection to the suture second line, "not elastic"should be "non-elastic" ; p. 522, tracks is not so simple as is generally believed. My col. twentieth line, " abstract quantity " should be 2, paper referred to the danger of cancer infection and "abstract quality." I would not have troubled about these its importance in relation to the question of "recurrence." trivial mistakes only I am dealing with two soi-disant philoI tried to demonstrate that the cancer cell is infective, and and I don’t wish even a printer’s error to creep into, sophers if set it be therefore free at the time of operation it is liable letter. I am, Sir, yours faithfully, to be implanted by the surgeon or else implant itself in some my JAMES BARR. Liverpool, Feb. 15th, 1908. the wound and thus rise to a fresh cancerous of give part I outbreak. The cases of suture star nodules quoted were To the Editor of THE LANCET. given as illustrations of how readily cancer cell implantation ’ may occur and also as some of the possible ways in which SIR,-You have been so generous with your space that I forbear to reply categorically to Sir James Barr’s last letter, implantation may be brought about. In the course of my experience I have come across a great the more so that a detailed reply would involve much many varieties of infection of the suture tracks :in some repetition and probably weary your readers. That Sir James the infection was limited to the superficial and in others to and I differ profoundly on the subject of pulmonary physics the deeper layers of the skin ; and, again, it manifested is becoming more and more obvious. Sir James now asserts itself as a nodule deeply in the tissues directly in the that the tautness of the lungs does not exert traction, that course of the sutures ; and I have also seen it occurring the pulmonary tissue is not relaxed at the end of a full as infection of the entire track of the suture ; nevertheless, respiration, that the fibroid apices of the lungs in fibroid it is far from belief that these cancer I I recurrences " were phthisis do not drag in the chest walls, and that, no matter all due to infection having been carried there on the needle how many of the pulmonary vessels are destroyed in this or sutures. In Mr. Mansell Moullin’s case two sets of sutures disease, if "taut lungs constantly maintained a negative were used in closing the wound, one of stout catgut, interintrathoracic pressure there could be no obstruction to the rupted, passing through all the layers of the abdominal wall systemic venous circulation." (Not even if all the pulmonary except the skin; the other of finer catgut, continuous, capillaries were reduced to a single one !) In my opinion all through the skin only. Practically all the suture points of these contentions are wrong. the former series were infected; none of the latter. His It seems to me, Sir, that the time has now come for the -
JAMES
594 retire and consider the verdict. I have stated my I could and am content to let it stand as it is-unamended and unqualified. I am, Sir, yours faithfully, HARRY CAMPBELL. Wimpole-street, Feb. 16th, 1908.
jury to
case as
simply as
To the Editor of THE LANCET. SIR,-I have carefully read and re-read the correspondence between Sir James Barr and Dr. Harry Campbell, and the
conclusion I have come to is that it has been greatly confused through a lack of knowledge and precision on the part of the former in discussing the physical problems involved, and on the part of the latter through the use of unnecessarily complicated phraseology. The employment of the terms " tautness " and " traction by Dr. Campbell is peculiarly unfortunate, as they,’at "
least it appears
so much the word " tension." Tension is a state of strain, or the act of straining, and is a term perfectly well understood. Pulmonary tautness is a pulmonary state of strain, or tension. Pulmonary traction is a pulmonary act of straining, or tension. The word "tension" implies both the condition and the act. The tension of a wire means that it is tight and that it pulls ; and it would be absurd to worry over its tautness and traction, as both are stated or implied when one speaks of its tension. Dr. Campbell says I "fail to make the necessary disI purposely tinction between tautness and elasticity." avoided discussing the subject, but the distinction is obvious. There can be tension or tautness in a wire far beyond what its elasticity can produce or resist, or there may be tension or tautness less than what its elasticity can produce or resist, in which case the force of elastic recoil or tautness are equal. There can be tension or tautness in a fibroid lung as I am quite at one with Dr. well as in an elastic one. Campbell in distinguishing between tautness (or tension) and elasticity : where I differ is when he says that the negative I intrapleural pressure when the thorax and respiratory muscles are at rest " is due to the tautness of the pulmonary ’, tissue pure and simple, and that the factor of elasticity, or elastic recoil, has nothing to do with it." Dr. Campbell, like so many people who discover a truth, fails to see its limita-
more
so
to me, could both have been
easily expressed by
tions.
Suppose there be a large pneumothorax ; the lung recedes far from the body wall and rests contracted. Gradually, by vital processes, the air is absorbed, and as the chest walls cannot fall in so readily as the lungs can stretch, the latter expand and presently again fill the thorax. What stretched the lungs? Dr. Campbell says " the stretched condition of the pulmonary tissue is effected by the inspiratory muscles." I maintain that the cell action, or other vital processes which actively absorbed the air from the pleural sac, lowered the pressure in it and cleared the space for the lung to expand into, primarily caused its expansion, by decreasing the opposition to the action of the intrapulmonary air pressure. Likewise though at birth the lung is stretched by the thoracic expansion, the lung at, say, ten years of age is another lung, and I can conceive of no other way in which the new elastic tissue has kept on the stretch than by supposing it has been laid down on the stretch, or has contracted afterwards. In this way the elastic tension producing the intrapleural negative pressure, when the thorax and respiratory muscles are at rest, is generated within the lung, and in time would pull the visceral and parietal pleuræ apart if their lining cells would allow air or liquid to accumulate there and permit their separation. When the inspiratory muscles expand the thorax beyond the position of rest then it is that they obviously operate in lowering the intrapleural pressure. In addition to his employment of the words "tautness" and "traction " Dr. Campbell also seems to me unfortunate in his use of the word "suction." He does not use it as indicating a force decreasing the resistance to another force, as Sir James Barr rightly contends he should, but as though it were the force directly producing the effects observed. These are minor matters; the great principle for which Dr. Campbell has so earnestly contended-viz., the much overlooked importance of the action of the inspiratory movements in their effects within the chest, and the nature of these effects-he has done much to elucidate and establish, and I personally feel much indebted to him for what I have learned at his hands. In regard to Sir James Barr’s criticisms, it seems to me, after his letter of Jan. 25th, there is little to
be gained by discussing physics with him. gives from the 11 century Dictionary" a "
He there
definition A body is of elastic in which it is stated, perfectly elastic when it has the property of resisting a given deformation equally ......," and he remarks: "The Campbell physicist says it is a mere property of a certain form of matter, by which it has the power of recovering its original form after being stretched, but I prefer the other authority who says that it also signifies a resistance to stretching or other deformation." Now the other authority which Sir James Barr quotes and prefers does not say it "signifies a resistance to stretching or other deformation." The words are, it has the property of resisting," and it is this idea of a property which Dr. Campbell and I want Sir James Barr to admit. Surely it would be better if Sir James would " prefer" the definition of elasticity given by the authority from which he quotes, the " Century Dictionary," rather than his own misquotation from that authority. Sir James Barr shortly after proceeds in his letter to what he calls "prick the bubble " blown by Dr. Campbell, and he compares the uses of a "non-elastic chain" and what he terms "a hawser made of highly elastic hemp." He says : " The elastic rope offers resistance to being stretched and when the tug of the ship ceases the elasticity gradually pulls the vessel back to its former position." Sir James Barr should know that a hawser is made on the twist, and it stretches, not because hemp is what he styles "highly elastic," but because the component fibres and twists straighten out under tension, taking a direction more along the length of the rope than before and less across it, while at the same time mutually compressing one another. If Sir James twists a piece of string he will see that it shortens and will then lengthen when pulled upon more than before. The recoil in the hawser is due to the recovery of the parts from mutual compression and has nothing at all to do with elasticity in hemp. Moreover, if Sir James considers hemp highly elastic, why does he immediately speak of " nonelastic fibroid lungs "? By what mental process does he make hemp highly elastic and fibroid lungs non-elastic ? Later in his letter Sir James tells how he was selected by the Home Office to " devise a method of estimating the elasticity of any rope," and he modestly says, "Idid not retire to my study and work out the coefficient of elasticity, and what should, but probably would not, happen. I determined the vis viva or energy which I considered necessary, and then under a strain of a given number of foot pounds I determined the stretch, and I had no difficulty in devising a method of measuring the length of unstretched rope which would allow of a given energy." Fancy speaking of the length of unstretched rope which would allow of a given energy! Energy is the "capacity for doing work," and is measured by the amount of work a body having energy can be made to do. What capacity for doing work is inherent in a piece of unstretched rope. Would it allow of boiling a kettle or climbing a hill ? It would have been far better if Sir James Barr had retired to his disparaged study and learned the elements of physics as taught before hastily experimenting. He might then have started with ideas of energy, elasticity, &o., which were physically precise. Sir James Barr’s criticism in your last issue of my letter of Jan. 25th calls for little comment. He seems to hold me responsible for the consequences of the physical definition He says : "Let us see how his definition of elasticity. works out." It is nothing to me how my definition works out and what confusion or sadness it produces in the mind of Sir James. If he discusses physics as a physicist he must take the consequences, however they work out; if as the man in the street " he may call hemp highly elastic, rubber more elastic, and gas most elastic, but he must pose in future as the "man in the street " and not as a physicist. I will leave my last letter and Sir James Barr’s criticism of it to the impartial judgment of your readers as this communication is already too long, but I hope more particularly that Dr. Campbell’s suggestive views may have the attention which I think they deserve. I am, Sir, yours faithfully, D. W. SAMWAYS. Mentone, Feb. 17th, 1908. The various this *** parties to correspondence have had ample space in which to expound their views, and none of them can complain of the undue vigour of their opponents’ language, for none of them has failed to reply with equal vigour. As they cannot all have the last word we supply it. This interesting discussion must now cease.-ED. L. ’’
"
"
I
"