Top Seam Research Articles

Disposable, plastic unit for barium-enema examination.

When one considers the strict precautions taken in most hospitals and private offices to prevent cross-infection between patients, it seems absurd that so little has been done to make the barium-enema examination safer, if not esthetically more acceptable. The former practice of refilling the same enema can and tubing for successive patients during a morning's fluoroscopic session has not been rendered much less revolting by the ruse of allotting to each patient a freshly autoclaved enema tip or even a disposable plastic one. Anyone who has used clear plastic tubing to connect the enema can and the rectal tip is aware that grossly visible fecal material frequently refluxes from the filling colon well into the tubing and may even reach the enema can. The customary use of a metal can and rubber tubing, hiding this fecal reflux, may have served to keep our consciences clean, but little else. In two recent articles in the Journal of the American Medical Association (1, 2) attention was called to the very real danger of cross-infection as a result of the deposition of bacteria refluxed with the barium mixture from the colon into the tubing and can of the barium-enema apparatus. This occurs particularly when the colon goes into spasm, but it may happen when the patient simply coughs or changes position. Although little documentation of the spread of enteric disease by this method has been published, it may well occur. Certainly, the medieval filth of the present situation requires a more satisfactory technic for barium-enema examination. For several years we have provided a freshly autoclaved barium-enema can and tube with a disposable plastic rectal tip for each patient. Although this was a vast improvement over apparatus washed in soap and water, it involved a considerable number of cans and many feet of cracked tubing. An inexpensive, completely disposable unit (reservoir, tube, and tip) made of plastic is probably the ideal solution. Increasing dissatisfaction with the existing methods led our Department of Radiology to request such a disposable unit, which was designed for us by the Director of Pharmaceutical Research and Development at the Massachusetts General Hospital and then manufactured by a hospital equipment company5 in sufficient quantity for a pilot study. The one-piece unit consists of a 1 1/2-quart reservoir, 6 feet of tubing, and a rectal tip. A wire spreader in the top seam of the bag also serves as a hook by which it may be suspended. The entire unit is made of polyvinyl chloride and individually packaged in a plastic envelope (Fig. 1). Filling of the colon is controlled by a Kelly clamp. The tubing can easily be cut for the connection of a two-way system for air-contrast examinations or a retention catheter by means of plastic adapters.

The distribution of coal volatiles in the South Wales Coalfield and its probable signifinance

Summary The variation of volatile contents in seams in a horizontal sense is shown on an isovol map constructed by the Fuel Research Board following on a coal survey of the South Wales Coalfield. Nine vertical sequences of seams were also assembled, giving the volatile contents of each seam and its depth below a top seam assumed as a datum. For each of these sequences the constants and coefficients in each of four hypothetical relations were found by the least-squares method; these four hypotheses are: Hilt's law, the square-root relationship proposed by F. M. Trotter, the exponential relation suggested by H. W. Wellman between the ratio of the volatiles to fixed carbon and the depth, and another exponential relation between the volatiles and the depth. When applied to calculate the volatile contents of the other seams in the sequences all these relations gave results which did not differ significantly. The sequences cannot therefore give a verdict in favour of or against any one of the above hypotheses. The fact of greatest interest that emerged is that the coefficients for each expression vary so widely from one part of the field to another that no expression which uses a fixed value for its coefficient can be applied successfully to the coalfield as a whole. A surprising empirical relation was found, however, between these varying values and the mean volatile contents over which they hold, and from this expressions were derived which enable the volatile contents of any seam to be calculated or predicted if its depth below any other seam of known volatile content is given. These calculations are independent of any theory and the same value is obtained whichever of the above expressions is used if its coefficient and constant are determined by standard methods. The intimate relation between volatile contents and depth has been used to construct a contour map showing the depth of the Nine Feet Seam below an assumed datum of a seam with a 40 per cent volatile content. It is considered that this extremely intimate relation between volatile content and depth can be explained only by the hypothesis that the changing conditions which obtained when the seam was buried to varying depths are responsible for the variation of volatile contents. These relations are applied to certain problematic areas in the coalfield.

“Washouts” in the Estuarine Series of Yorkshire

The Middle Jurassic of Yorkshire consists of non-marine strata, known collectively as the Estuarine Series, and several intercalated marine bands. The non-marine beds have the characteristics of deposits formed as a delta rather than in an estuary, and are, in fact, strongly reminiscent of the Coal Measures in their general appearance. In the coast section, where they are admirable exposed, which are usually due to the presence of false bedded sediments replacing the normally parallel bedded strata. Thick wedges of sandstone replacing the Dogger, and sometimes part of the Upper Lias too, have been described by Dr. Rastall and Fox-Strangways. They are particularly noticeable when they interrupt the top seam (i.e. the Dogger) in the iron mines, where they are called “freestone baulks” by the miners. The same phenomenon is better known in the Coal Measures, where the term “washout” is used for a mass of sandstone suddenly replacing coal. Although there are several objections to the term “washout”, it is used here since it had become so well established in Coal Measures geology.