An introduction to medical literature, including a system of practical nosology : intended as a guide to students, and an assistant to practitioners / by Thomas Young.

  • Thomas Young
Date:
1813
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to medical literature, including a system of practical nosology : intended as a guide to students, and an assistant to practitioners / by Thomas Young. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

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    term, for a criterion of the quality of a fleece, can tend only to the propagation of error or conjecture in the semblance of the minutest accuracy. Even with the Eriometer, the difficulty of obtaining a fair average of the quality of a sample of wool is extremely great; it is absolutely neces- sary to preserve the fibres as much as possible in their na- tural relative situation, and to examine them near the middle of their length ; the ends next the skin are almost always consider- ably finer, and the outer ends generally coarser, than the rest, but this difference is greater in some kinds of sheep than in others, and as far as I have observed, it is less in the Merinos and their crosses than in other sheep: there is also far less differ, ence in the different parts of the same fleece in these breeds than in others; still however this difference is very observable, al- though it is probable that some part of the sheep might bie found, which in all cases might fairly be considered as affording nearly the average of whole fleece ; and I imagine that the part of the back about the loins is the most likely to be possessed of this property; so that the middle of the fibres of this part of the fleece might be assumed, in the finer kinds of wool, as afford- ing a fair measure for the whole. 3, Scale of the Eriometer. The theoi-y, which suggested to me the construction of the eriometer, requires some corrections in its immediate applica- tion, which depend on circumstances not completely under- stood : at present therefore I shall only employ, for the deter- mination of the true value of the numbers of its scale, an expe- rimental comparison of its indications with some microscopical measurements, which Dr. Wollaston has been so good as to per- form for me, with an admirably accurate micrometer of his own invention. The dust or seed of the lycoperdon bovista he finds to be ■gT>x;Tj of an inch in diameter : this substance gives very distinctly 3.5 on the scale of the Eriometer; and 3.5 x 85000=29750. The] globules of the blood measured -^q-q ; and immediately