The following extracts are from the experiments and conclusions of
Rumford, with supplements by Prof. Mattieu Williams, of England. (See
"Knowledge," Nos. 171 to 205, "Philosophy of Clothing.")
The physiological confirmation of these results are not quoted;
confining the citations to the qualitative value of fibres, especially
sheep's wool, and the possibility of materials therefrom that possess
the _essentials_ recommended.
The first use of clothing being to keep the wearer warm, Rumford's
first inquiry was directed to find the best material for this purpose.
He saw at once that clothing did this by resisting the passage outwards
of the animal heat.
He accordingly constructed a model wearer, as described in the
following experiments: A mercurial thermometer, whose bulb was 55/100th
of an inch in diameter, and its tube about ten inches long. This was
suspended in the axis of a cylindrical glass tube about three-quarters
of an inch in diameter, ending with a globe 1-6/10 inch in diameter,
in such a manner that the center of the thermometer bulb occupied the
center of the globe, thus leaving a surrounding space to be occupied by
the material to be examined. The thermometer tube was graduated with
800 divisions between the freezing and boiling points of water--_i. e._,
a Reaumur scale divided to tenths of degrees. The thermometer was
held in its place by a long cork stopper.
He described his method of clothing the bulb as follows: The
thermometer being taken out of the cylindrical tube, about two-thirds
of the substance which as to be the subject of the experiment is
introduced into the globe; after which the bulb of the thermometer
introduced a few inches into the cylinder; and after it, the remainder
of the substance being placed round about the tube of the thermometer:
and lastly, the thermometer being introduced further into the tube, and
being brought into its proper place, that part of the substance which,
being introduced last, remains in the cylindrical tube above the bulb
of the thermometer, is pushed down into the globe, and placed equally
round the bulb of the thermometer by means of a brass wire, which is
passed through holes made for that purpose in the stopple closing the
end of the cylindrical tube.
The temperature he selected as the starting point was 70 degrees
Reaumur=190 degrees Fahr. He preferred this to the boiling point, as
he could obtain it accurately by first plunging the whole apparatus
duly charged into nearly boiling water, then allowing it to fall to 70
degrees, and immediately plunging it into a mixture of pounded ice and
water, where, by the aid of a little agitation, it remained steadily at
the freezing point.
The following table shows the results with the substances therein
mentioned, the quantity in each case being 16 grains:
============+===========+=============+============
|RAW SILK AS| |
HEAT LOST. |SPUN BY THE|SHEEP'S WOOL.|COTTON WOOL.
| WORM. | |
------------+-----------+-------------+------------
70° | -- | -- | --
60 | 94´´ | 79´´ | 83´´
50 | 110 | 95 | 95
40 | 133 | 118 | 117
30 | 185 | 162 | 152
20 | 273 | 238 | 221
10 | 489 | 426 | 378
------------+-----------+-------------+------------
Total times | 1,284 | 1,118 | 1,046
------------+-----------+-------------+------------
The clothing value or "warmth" of these substances as thus applied
varies directly with these figures, representing the passage of heat or
their "non-conducting" power.
The experiments described were directed to the determination of the
relative power of different materials. (We have only quoted the
substances most generally used for clothing purposes.) These were
followed by another series upon certain given materials differently
arranged, or in different conditions of density. The same "passage
thermometer" was used. The question to be determined was, whether the
protecting power of the substances used in the previous experiments
was due to the non-conduction of the material of those substances
themselves, or whether the air imprisoned between their fibres was an
important factor. If the silk, wool and cotton did all the obstructive
work independently of the air, then the amount of obstruction should
vary with the quantity of fibre. As, in the experiments already
described, the fibres were loosely arranged round the bulk of the
thermometer, it was easy to increase their quantity by packing them
more closely, and yet retaining the other conditions of bulk, etc., the
same.
It was evident from the results, with 16 grains, 32 grains, 64
grains, that the protective power does not increase nearly in the
same proportion as the quantity of material when packed in the same
space. Had such been the case, and the rate of cooling proportionately
retarded, the experiment (with eider down from the duck) with 64 grains
should have been 1,304x4 5,216 seconds, instead of only 1,615 seconds.
The following displays the results obtained by using the same material,
in same quantity, but differently disposed, 16 grains of each:
--------+------+--------+-------+------+------+------+------+------+-----
| |Sewing | | | | | | |
| |or | | | | | | |Linen
Heat | |knitting| |Woolen| |Cotton| |Linen |Cloth
lost or | |silk | |Thread| |Thread| |Thread|wrap-
amount | |wound |Sheep's|wound |Cotton|wound | |wound |-ped
of |Raw |round |wool, |round |wool, |round |Lint, |round |round
cooling.|Silk. |bulb. |loose. |bulb. |loose.|bulb. |loose.|bulb. |bulb.
--------+------+--------+=======+======+------+------+------+------+-----
70° | -- | -- | -- | -- | -- | -- | -- | -- | --
60 | 94"| 46" | 79"| 46"| 83"| 45"| 80"| 46"| 42"
| | +-------+------+ | | | |
50 | 110 | 62 | 95 | 63 | 95 | 60 | 93 | 62 | 56
| | +-------+------+ | | | |
40 | 133 | 85 | 118 | 89 | 117 | 83 | 115 | 83 | 74
| | +-------+------+ | | | |
30 | 185 | 121 | 162 | 126 | 152 | 115 | 150 | 117 | 108
| | +-------+------+ | | | |
20 | 273 | 191 | 238 | 200 | 221 | 179 | 218 | 180 | 168
| | +-------+------+ | | | |
10 | 489 | 399 | 426 | 410 | 378 | 370 | 376 | 385 | 338
--------+------+--------+=======+======+------+------+------+------+-----
Tot. | | | | | | | | |
times. |1,284 | 904 | 1,118 | 934 |1,046 | 852 |1,032 | 873 | 786
--------+------+--------+-------+------+------+------+------+------+-----
From this it is to be seen that sheep's wool loose would retard the
passage of heat more perfectly than when spun into thread.
THE "JAROS HYGIENIC MATERIAL" _of sheep's wool unspun worn next the
body possesses the essentials for non-conduction of heat in a manner
described_.
It is an instance how an effort to apply pure science to practical
business may react in such manner that practical business shall become
a beneficent contributor to pure science.
Another practical question suggested is: Whether clothing materials
differ in their powers of absorbing the cutaneous exhalations; if
so, which are the most effective, and what are the relations of
this function to that of confining air, and thereby maintaining the
temperature of the body? If these two functions are opposed, then how
shall we effect a compromise? If, on the other hand, they go together
in any special material, the desirability of using this material is
doubly indicated.
_Sheep's wool_ does absorb (see Knowledge 191) the aqueous vapor.
Loosely distributed fibres of wool in a suitable fabric take hold of
the vapor of the insensible perspiration in the gaseous form, and by
virtue of gaseous diffusion continually exchange this with the gasses
of the outer atmosphere.
The conclusion, therefore, is that such a material is best suited for
clothing, both in winter and summer.
Sir John Billingall (lecturer on Military Surgery) mentions his
experience in India, and the proof of the utility of wool in checking
the progress of a most aggravated form of dysentery in the Second
Battalion of the Royals. The result of this has led to the enforcement
of the use of belts for tropical service. Mr. Sage of the Army Clothing
Depot at Pemlico, tells me many thousands have lately been made there.
My experience and subsequent observations have proven that, although
loosely woven flannels may advantageously prevent the sudden chills
from the evaporations of accumulated perspiration, this is better _done
by a knitted fleecy wool fabric worn next the skin_.
JAROS HYGIENIC MATERIAL,
WOOL FLEECE KNIT.