Observations upon the construction and use of the respirator : an instrument for facilitating respiration, to be worn on the face by persons suffering from coughs, consumption, asthma, and other affections of the chest / [Julius Jeffreys].

Date:
1836
Catalogue details

Licence: Public Domain Mark

Credit: Observations upon the construction and use of the respirator : an instrument for facilitating respiration, to be worn on the face by persons suffering from coughs, consumption, asthma, and other affections of the chest / [Julius Jeffreys]. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    matter afforded data upon which it was easy to proceed with confidence of a successflil residt. In the first place, the lightness of air is such, that sixteen grains may be taken as the full weight of the air of each respiration. Secondly—The capacity of air for heat is small, so that any substance which is to take up the heat of tem- perature of sixteen or twenty grains of warm air, need not itself weigh much. Thii’cUy—Though air is a had conductor of heat, its ready divisibility affords a way of exposing siimd- taneously all its parts to the action of the substance which is to conduct off its heat. Fourthly—Its mobihty and elas- ticity, together mth this divisibility, ai'e so complete, that they enable it to pass readily through very small apertrues, if tliese apertures are not long or tubular; and as these apertures (for the purpose of the third indication, i.e., for rapid conduction,) must be very numerous, the motion need not be perceptibly obstmcted. There may even be many layers of the conducting substance, provided the layers be very thin. Fifthly—Not only may the ready passage of the air be thus seemed, but even those minute vibrations in it, which constitute the voice, may be preserved, if the conducting substance it traverses be metallic. Air will not have its most dehcate vibrations distrubed by passing through many metallic plates, well perforated, however small the apertures. AVliereas, by plates of fibrous substances, as paper or pai'chment, which themselves vibrate with vocal sovmds, the voice is deadened. Sixthly—As for the vocal effect the conducting substance ought to be metallic, so does the main principle of its action require that the depository of the heat shoidd be formed of matter of the best conduct- ing power. Hence, on this accoimt, also, it must be of metal. The two indications are thus in happy accordance; and silver, as the substance whose conducting pi-operty is neaidy the gi-eatest, may be employed. Seventhly—Since the tempera- ture of any one substance must be lower than that of any other before it can receive heat from the latter by conduc- tion, it is plain that a single sheet of perforated metal could only take a pail of the heat fi-om the breath; even if the con- tact were longer than it is, the breath woidd lose no heat after it had raised the metal up to its o\to temperatiue. In order to exfract more heat fr’om the breath, it must be caiTied through another layer of metal, which being much colder than itself, can abstract heat fr'om it. As the breath and this second layer approach towards the same temperatiue, this second layer will not be able to abstract more heat fi'om the