On the form of the intraventricular and aortic pressure curves obtained by a new method / by W.M. Bayliss and Ernest H. Starling.

  • William Bayliss
Date:
[1894?]
Catalogue details

Licence: Public Domain Mark

Credit: On the form of the intraventricular and aortic pressure curves obtained by a new method / by W.M. Bayliss and Ernest H. Starling. Source: Wellcome Collection.

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    found below. This is connected by narrow lead tubing to a threeway stopcock, from which on the one hand a tube proceeds to a pressure- bottle, containing 25 °/0 magnesium sulphate solution, and on the other to a short piece of lead tube, soldered to a brass nozzle, which fits into a brass stopcock at the end of the heart catheter. By this means, the capillary tube can be put into connection, either with the pressure bottle or with the heart cavity. To prepare the instrument for use, the point of the capillary being open, fluid is run in from the pressure-bottle, until a small air-space is left at the top, and the point is then sealed by a flame, so that the cavity is closed. The meniscus at the junction of the air and fluid is then focussed by a Zeiss A. microscope objective on to the surface of a photographic film attached to a rotating cylinder, a lime-light lantern being used as source of light. Between the microscope lens and the cylinder, there are interposed — 1st- a shutter for convenience of exposure; and, 2nd- a narrow vertical slit. The image of the slit being focussed on the film by a cylindrical lens, gives a very fine sharp line of light, broken by a dark band where the image of the meniscus falls. One boundary line of the band can be focussed quite sharply by means of the fine adjustment of the microscope. A tuningfork of 50 vibrations per sec. with a slip of paper projecting from one limb across the slit, serves' to register the time. The films found most convenient were Edwards’ Isochromatic Instantaneous and were developed by Eikonogen. The dimensions of the air-space were the following: Length.3 8 mm Diameter.0 3 mm therefore volume ~0 268 cub. mm. It is well at the outset to state that we do not lay any stress on absolute measurements of pressure made with this instrument, for two reasons: 1st- It is impossible to obtain accurate measurements of the dimensions of the air-space, and the capillary is probably very slightly conical in form, and: 2ndly- We pave no means 0f knowing how far the compression of the air takes place adiabatically. If the pressure-bottle is quickly
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