835CAISSON DISEASE IN THE LIFFEY TUNNEL.

animals indicate the greater facility with whichtetanus can be imposed on vaccinia when the lesionsare covered with a dressing, and also when the virusis inserted by intradermal injection. Post-vaccinaltetanus is, of course, very rare in this country, butthe problem of the appropriate dressing is none theless important, since severe " takes " are definitelystated to ,be more common when the lesions are

covered. Armstrong, it may be noted, recommendsvaccination by the " multiple pressure " method ofJ. P. Leake,2 and holds that there should be nodressing, or at most only a loose sleeve. £

ANOTHER ANÆSTHETIC FOR CHILDBIRTH.

BARBITURIC acid derivatives have been used as

anaesthetics or analgesics in France, where somnifen(allyl-isopropyl barbiturate) has had a certain vogue,and in Germany, where Bumm introduced pernokton,a brom-propyl-phenyl barbiturate. Somnifen hasbeen used both intravenously and intramuscularlyin labour, but has been condemned by some as

causing drowsiness in the child and extreme restless-ness in the mother. The progress of labour was alsoheld to be impaired. The latest drug of this kind tobe employed is sodium iso-amylethyl barbiturate,3 3and after extensive trial on animals a hundred casesof labour have been conducted with its aid. It wasgiven intramuscularly after an injection of morphineand scopolamine when uterine contractions were

occurring at intervals of less than ten minutes.Later intravenous injections were given. It is statedthat labour was rendered almost painless withoutany evidence of harm to the mother, that danger tothe baby has not been proved, and that prompt andcomplete control of eclamptic convulsions is possible.The most serious objection to the use of sodiumamytal was the difficulty in restraining patients whobecame very restless. The drug is rapid in actionand has a wide range of safe dosage.

CAISSON DISEASE IN THE LIFFEY TUNNEL.

CAISSON disease is caused by liberation of nitrogenbubbles from the blood into the tissues when a tunnelworker or diver passes too quickly into the normalatmosphere from a zone of high pressure. It is usuallyavoided by allowing the workman to pass through achamber or " lock " in which decompression takesplace gradually, but Dr. F. J. O’Donnell 4 relatesthat no less than 25 of 69 men employed during11 months at the tunnel face in the Liffey Tunnelat Dublin suffered from " bends," as the symptomsare commonly called. One of them developed organicparaplegia, due to nitrogenous bubbling and coalescencein the fatty and vascular structures in the lowerdorsal spine, and three presented intractable jointand visceral pain unfitting them for further work ofthe kind. In ten cases severe disablement wasavoided only by immediate recompression, andthere were 11 cases of arthralgia, vertigo, headache,and cramp. From a study of this high morbidityand of the men who escaped it, Dr. O’Donnell hascome to the conclusion that damp and cold greatlyadd to the risk of the disease ; in a warm dry site,he says, no cases should occur with pressures up to301b. per square inch, provided that decompressionis gradual. He holds that shifts should be shorter,the longest period which should be passed in " air "being not more than three hours. Extra clothingand stimulant drinks should be available during andimmediately after decompression, and workers shouldnot quit the vicinity of the decompression lock tillthey have been free from all abnormal sensations for

2 Ibid., 1927, xlii., 221 ; see also THE LANCET, 1927, i., 671.3 Robbins, A. R., McCallum, J. T. C. , Mendenhall, A. M., and

Zerfas, L. G.: Amer. Jour. Obst. and Gyn., Sept., 1929, p. 406 ;see also THE LANCET, Oct. 5th, p. 730.

4 Irish Jour. Med. Sci., 1929, xlv., 618.

fully half an hour. Men with a systolic blood pressureof over 140 are unsuitable for training in work underhigh pressures and should be rejected as recruits,but individual susceptibility to " air " varies con-siderably and apparently cannot be foretold by anydevice, so that newcomers should be tested in an air-lock on the surface or given graduated shifts. A com-plaint of itchiness of the skin among seasoned andexperienced workmen who feel no other ill-effects isa sign that they have been exposed as long as isadvisable and they should be given a short rest.

SMOKE ABATEMENT.

AT a conference recently held in Buxton a fusiontook place of the societies known as Coal SmokeAbatement Society and the Smoke Abatement Leagueof Great Britain, under the presidency of Dr. H. A.des Voeux. It had been recognised for many

years that concentration of the work in one body wasadvisable in order to save duplication of effort anddissipation of energy. Certain difficulties whichstood in the way have now been overcome and thereis every hope that the formation of a NationalSmoke Abatement Society will secure the diminutionof the clouds of smoke which are so evident to anytraveller by train or road and especially by air.We trust that one of the first tasks undertakenby the Society will be to impress strongly on

all sanitary authorities the importance of applyingthe by-laws which can now be made under the SmokeAbatement Act of 1926. We understand that of allthe authorities in the country only between 70 and 80have as yet applied to the Ministry of Health forsanction for by-laws, and of these many governsmall and unimportant districts where the nuisancefrom smoke is little felt. The Smoke AbatementAct, although not drastic enough to satisfy enthusiasts,admits of progress in the right direction, and theMinistry has circulated to all authorities a modelby-law which fixes the standard time for the per-missible emission of black smoke as two minutes inhalf an hour. The wording of this model by-law isas follows :-

" Whereas Section 2 of the Public Health (Smoke Abate-ment) Act, 1926, provides that any local authority maymake by-laws regulating the emission of smoke of suchcolour density or content as may be prescribed by theby-laws and that where such by-laws are in force theemission of smoke of the character so prescribed for suchperiod as may be prescribed in the by-laws either frombuildings generally to which the enactments relating tosmoke nuisances apply or from any such classes of thosebuildings as may be so prescribed shall until the contrary isproved be presumed to be a nuisance :-

" The Mayor Aldermen and Burgesses of the Boroughof X, acting by the Council (or, as the case may be, the Urbanor Rural District Council of Y or Z) do by this by-lawprescribe that the emission of black smoke for a period oftwo minutes in the aggregate within any continuous periodof thirty minutes from any one chimney in a buildingother than a private dwelling-house shall until the contraryis proved be presumed to be a nuisance."

The advantage of such a by-law is that a sanitaryauthority can, through its inspector, go into a courtof justice and give evidence that black smoke hasbeen emitted for a period of two minutes in theaggregate in half an hour. This simple procedurecan now be adopted by all sanitary authoritiesthroughout the Kingdom, and if faithfully anddeterminedly followed should do much to mitigatethe smoke nuisance of factory towns and districts.The knowledge that such power exists will doubtlesseducate owners of factories to a proper sense oftheir duties to other citizens, and it is hoped that fewprosecutions will be necessary. The Ministry of

, Health has so far not allowed any by-law dealing withsmoke other than black smoke. But although it isincontestable that atmospheric pollution is mostintense where factories exist, a considerable propor-

tion of smoke does come from domestic chimneys,,

and much work remains to be done in stimulatingthe demand for smokeless methods of heating the