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of nature. No observer would be willing to risk the value of this long labor by trusting to the new barometer, until its peculiarities are better understood than at present. It may possibly happen, that a long series of observations which eliminates irregularities of weather will eliminate instrumental irregularities at the same time. The same objection applies with greater force to the application of the aneroid barometer to the measurement of heights above the level of the sea. An elevation of eighty-seven feet depresses the barometer by about .l of an inch only; hence, a small error in the barometer will entail a large error on the estimated elevation. Moreover, a long series of observations in this case will generally be impracticable. I would make one farther remark in this connection. The mercurial barometer is liable to be broken when exposed to the perils of mountain travel. In this case the damage, though great, is known and appreciated, and no error is introduced into science. Unless the barometer is broken, it is so simple in its construction that it is not likely to be injured at all. It is otherwise with the aneroid barometer. To appearance it is stronger, and can bear a greater strain without being broken. On the other hand, we can easily foresee that it may be materially injured without attracting the notice of the observer at the time, and in this way may conceal its own infirmities under its apparent strength. It should be added, in justice to the aneroid barometer, that it is far from having been carried as yet to that degree of perfection in its mechanical execution which the principle on which it is based will allow. When it shall have received, at the hands of the artist, that amount of skill and delicacy in its construction which is expended on the chronometer, a more impartial comparison can be made between its claims and those of the best mercurial barometers.”

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Dec. 4. The aneroid barometer was placed under the receiver of a condensing-pump, when it was observed that it would only move up to thirty-one inches (corresponding to thirty-one inches of a common barometer).

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Dec. 10,

11,

12,

14, 15,

16,

20,

29.932 30.089 30.439 30.267 30.122 30.378 30.148 29.870 30.327 30.519 29.703 30.119 30.012 29.353 29.595 29.488 30.212 30.087 30.407 30.025 30.200 30.115

29.977 30.107 30.507 30.237 30.117 30.397 30.147 29.907 30.327 30.537 29.787 30.127 30.067 29.447 29.667 29.597 30.310 30.160 30.447 30.090 30.197 30.147

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30.360 30.407 30.156

30.207 29.890 29.937 30.125 30.137 30.464 30.517 30.340 30.367 30.098 30.138

30.098 Difference, .040—

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Mean,

VOL. II.

25

TABLE III.

Observations in Table II., arranged according to the Amount and

the Sign of the Differences.

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Table IV. 1849, Sept. 10. The aneroid stood at 30.39. It was placed under the receiver of an air-pump, and the atmospheric pressure diminished by five inches. When the air was admitted, the index moved forward to 30.35. It rose to 30.375 in two or three minutes. The following table embraces similar experiments, with their results.

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Dr. C. T. Jackson exhibited some specimens of native copper, and gave a verbal account of some of the evidences of ancient Indian mining at Lake Superior. Dr. A. A. Hayes stated that the occasion of these samples being on the table was a proper one for him to take, in communicating the fact, " that, from extended observations, embracing more than five hundred specimens of the Lake Superior native copper, no instance occurred in which the slightest indication was presented of this copper having been fused in its present condition. I have investigated its internal structure, by a new method of analysis, which permits all alloys and foreign matters to fall on one side, while the pure copper is separated and weighed as such on the other. In this way, and by little modifications, the highly crystallized structure is exposed to view, the less regularly polarized portions being removed. Whether we subject the solid thick masses, or the thinnest plates, to the operation, one constant result is obtained ; - that this copper has taken its present varied forms of crystallized masses, more or less flattened, laminated, or grooved, by the movements among the parts, composing the rocks in which it is found. If we select a mass which has entered a cavity, we find the crystals with their angles sharp and uninjured, while the mass mainly may have been compressed into a plate. Dis. secting this, the crystals are seen to be connected with and form parts of the original system of crystallization. Flattened and grooved specimens often present on their edges arrow-head-shaped forms, derived from regular crystals, crushed and laminated.”

Dr. Hayes, having alluded to a new method, a kind of proximate analysis of metals and alloys, further stated, that it is one which admits of almost universal application. Operating on irons of commerce, he has demonstrated that phosphorus and sulphur, usually found to be present, are not united to the iron, but with more highly electro-positive metals, such as potassium, sodium, and calcium, the latter most commonly. And in all alloys thus far examined, the compound is a metal in a pure homogeneous state, while one, two, or three definite alloys are distributed, often unequally, throughout the mass. In some tough metals, brittle substances like iron ores, quartz, &c., are found, rendering the method of research one of great interest and importance.

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