|LETTER TO THE EDITOR
|Year : 2013 | Volume
| Issue : 6 | Page : 643-645
The smoked drum
Gurudas Khilnani1, Rekha Thaddanee2, Ajeet Kumar Khilnani3
1 Department of Pharmacology, GMERS Medical College and Hospital, Dharpur, Patan, Gujarat, India
2 Department of Pediatrics, GMERS Medical College and Hospital, Dharpur, Patan, Gujarat, India
3 Department of ENT, GMERS Medical College and Hospital, Dharpur, Patan, Gujarat, India
|Date of Web Publication||14-Nov-2013|
Department of Pharmacology, GMERS Medical College and Hospital, Dharpur, Patan, Gujarat
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Khilnani G, Thaddanee R, Khilnani AK. The smoked drum. Indian J Pharmacol 2013;45:643-5
Kymograph, consisting of a revolving drum, bearing a record sheet (usually of smoked paper) on which a stylus moved up and down displaying the effects of the drugs on contractile tissues, was commonly used in experimental physiology and pharmacology laboratories in teaching institutions. Nowadays, these are conspicuous by their absence. Mechanical kymograph was invented by German physiologist Carl Ludwig (1816-1895) in 1847. Pioneers such as Sir Charles Scott Sherrington (1857-1952) and Ernest Henry Starling (1866-1927) developed the smoked drum. It was manufactured by C. F. Palmer Limited (London) in 1932. Sherrington Starling recording drum was used with a kymograph to record activities such as heart and skeletal muscle contractions. Many teaching institutions and laboratories still use the Sherrington Starling Recording Drum today. Physiologists first used kymographs for recording blood pressure. Experimental psychologists adopted the kymograph as an instrument for recording various body responses in psychiatry. 
The recording drums originally made of brass (15 cm diameter) rotated mechanically, were later modified so that steel drums could be driven by electrical motors. The speed of rotation (eight variable speeds) was regulated by adjustable hand gears and use of clutches. Double electric contact arms were clamped on the main spindle and a stout double-contact block fitted on top of the base. A single motor could move a long horizontal shaft (with the help of belt), which had gears and pulleys at intervals so that a number of drums could be rotated simultaneously. Later kymographs with individual motors were available. The drums rotate clockwise therefore tracings are obtained horizontally from the left side to the right side of experimenter. These days they are not put to regular use because of restrictions on animal experiments for undergraduate (UG) medical training. Yet the Medical Council of India still recommends the use of these kymographs as minimum standard requirement for UGs! Large extension kymographs Brodie-Starling type complete with respiration pump can be found in nooks and corners of many laboratories.
A frontal writing lever (Type-1 lever) has been one of the most commonly used levers for making a continuous contact of stylus on the smoked drum and getting vertical tracings for bioassay. Originally, a recording lever was made of nickel plated brass, size 18.5 cm (C F Palmer Ltd., London c1934-1968). A number of modifications were used to reduce friction and improve contact of lever with the drum. One such modification performed was the straw lever, indigenously devised by professor S K Sharma in JLN Medical College, Ajmer. It was easy to make. A straw holder was used to hold a thin straw. It consisted of a light weight bamboo straw of about 20-25 cm length. The tip was slit open with a surgical knife and a small rectangular piece of card-sheet (post card thick) snugly slid along its breadth and adhered to it. A hinge was made on the rectangular paper about half a cm below the point of attachment with straw by cutting and resealing with a cello tape. This provided elasticity and spring like action to the writing end. A thin wire of about 2 cm was taken and folded at one of its ends. This end, bent at a right angle, was used as a writing point on the smoked drum. The other end of wire was inserted into the card and secured by cello tape. This indigenously made lever worked for years once in use. Many more modifications are reported. A wax paper in place of smoked paper was suggested for use by Gerbrands and Volkmann.  One could use a simple glazed paper without smoking, but the ink writing pen device would be required for obtaining tracings. A simple ink writing pen system for kymographic recordings was developed by Pantic and Pantic.  Continuous ink-writing kymograph unit for teaching and research in veterinary physiology and pharmacology was developed by Stone and Klavano.  Petersen used a capillary ink pen for writing on kymograph paper.  A pen-vibrator adapter to increase the sensitivity of an ink-writing kymograph was also developed by Spencer.  One problem of ink capillary writing pens is the spilling of ink and blotting of paper when the drum is static. Obviously, it would not occur with the use of smoked drum.
The preparation of the smoked paper, an art in itself, consisted of wrapping a blank sheet of paper over a kymograph drum and fixing drum on a horizontal rotating stand and exposing it to benzene or kerosene fumes in a chamber specially made for it and called smoking cabinet or chamber. A nice method was described by Bartlett et al.  During rotational movements a thin uniform layer of soot, neither too thick nor too thin, was deposited on its surface thus allowing a hard stylus made of aluminum or straw with a wire at the tip to make a contact with the drum as it rotates, leaving a line record. The smoked paper drum so prepared used to be mounted on the shaft of the kymograph and locked after adjustment of the level. The speed of the drum could be varied according to need from 12.5 mm/s to 25 mm/s (range: 0.12 mm/s-640 mm/s). How meticulous one had to be to get a horizontal baseline! The vertical movements of the stylus of lever left white tracings of the tissue activity on the smoked drum and thus it was easy to interpret the results of experiments. For a permanent record one had to "fix" the tracings. This was carried out by carefully separating the smoked paper from the drum carrying the smoked paper in both hands and passing slowly moving the paper in a puddle of fixing solution consisting of alcoholic solution of shellac, colophony resin or other varnishing solution. Drying the fixed paper was to be carried out very carefully lest the wet tracings were damaged. Once dried, the unwanted portion was trimmed off and the tracing was ready for study.
These age-old smoked drums and kymographs have enabled thousands of brilliant physiologists and pharmacologists in understanding basics of physiology and pharmacology like drug receptor interactions. As time passed, the smoked drums was replaced by physiographs and multichannel polygraphs. Those who were accustomed working with the friendly smoked drum kymographs and have started using students' physiographs know the difference. A major advantage of smoked drum was its simplicity and ingenuity. The height of smoked paper was over 20 cm and it was possible to obtain frog rectus contractions of 8 cm to 10 cm height easily. Thus doing 2 + 1 or 2 + 2 bioassay was an order, which gave a rich learning experience and a great degree of satisfaction. Today, doing 2 + 2 bioassay using physiographs becomes an ordeal through which even a bright post-graduate passes in agony. I don't see such good responses to be recorded on a graphed paper of physiograph. Of course these sensitive devices can record, amplify (50-100 times) and convert mechanical shifts into recordable signals, which can be digitally stored and retrieved. Furthermore, forgotten is the art of balancing a lever with the help of plasticine put on the short arm of the lever. The beauty was to make a fine balance as well to provide some degree of load to the contractile tissue against which it contracted optimally when stimulated by agonists!
I feel smoked drum is still a useful instrument, which need to be remembered as a good old benevolent friend and not an obsolete machine to be kept in the corner in complete oblivion. This write up should not be read merely as reminiscence of historical past or as nostalgic diction, but as an attempt to revive the art of experimental pharmacology, which is dying a slow death. And of course the smoked drum should not be mistaken with a smoking drum!
| » References|| |
|1.||Titchener EB. Experimental Psychology, a Manual of Laboratory Practice: Quantitative Experiments, Part II. Instructor's Manual. Vol. 1. New York: Macmillan; 1918. p. 172-6. |
|2.||Gerbrands R, Volkmann J. A wax-paper kymograph. Am J Psychol 1936;48:498-501. |
|3.||Pantic VS, Pantic SM. New simple ink writing pen system for kymograph recording. Indian J Physiol Pharmacol 1996;40:186-8. |
|4.||Stone EC, Klavano PA. Continuous ink-writing kymograph unit for teaching and research in veterinary physiology and pharmacology. Am J Vet Res 1952;13:579-81. |
|5.||Petersen P. A capillary ink pen for writing on kymograph paper. Scand J Clin Lab Invest 1958;10:111-2. |
|6.||Spencer HJ. A pen-vibrator adapter to increase the sensitivity of an ink-writing kymograph. Physiologist 1982;25:437-8. |
|7.||Bartlett FC, Borovski V, Kiesow F, Miles, Wilcocks RW. Apparatus for smoking kymographic drum paper. J Gen Psychol 1929;2:509-15. |
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