Tables, Meteorological and Physical: Prepared for the Smithsonian Institution |
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Page 66 - Corrections to bo applied to the Means of the Hours of Observation to obtain the true Mean Temperatures of the respective Days, Months, and of the Year.
Page 64 - Forces due to t and t', we have = ^~ = 73.4, Relative Humidity in Hundredths. The following Table VIII. gives, in hundredths, the fraction of saturation, or Relative Humidity, corresponding to each degree of f, or of the temperature of the air, from 0° to 104° ; and for every half degree of t — t', or of the difference between the temperature of the air and of the dew-point, from 0.°5 to 24.°5. Regnault's Table of Elastic Forces of Vapor, reduced to English measures, has been used in the computation....
Page 33 - The laws of the distribution and transmission of moisture through the atmosphere are too little known, and its amount, especially in mountain regions, is too variable, and depends too much upon local winds and local condensation, to allow a reasonable hope of obtaining the mean humidity of the layer of air between the two stations by means of hygrometrical observations taken at each of them. These...
Page 53 - T', or the Difference of the Temperatures of the Barometers at the two Stations. This Correction is Negative when the Temperature at the Upper Station is lowest, and vice vers i. T—V. Correction. T— T'. Correction. T — T1. ( Correction. T— T'.
Page 123 - REDUCING TO THE FREEZING POINT THE OBSERVATIONS TAKEN WITH OLD FRENCH BAROMETERS, PROVIDED WITH BRASS SCALES, EXTENDING FROM THE CISTERN TO THE TOP OF THE MERCURIAL COLUMN ; CALCULATED FROM 240 TO 345 LINES, OR FROM 23 INCHES 4 LINES TO 28 INCHES 9 LINES.
Page 50 - We then calculate the correction a.— '- — -- — for the temperature of the air, by multiplying the nine hundredth part of a by the sum of the temperatures t and t', diminished by 64.
Page 72 - GLASS SCALES, TO THE FREEZING POINT. IN most of the common barometers the scale is engraved upon a short plate of brass, or of ivory, fixed upon the wooden frame of the instrument. In such a case, the compound expansion of the two substances can only be guessed at, and the correction to be applied to the observations for reducing them to the freezing point cnnnot be determined with precision.
Page 83 - From the foregoing statements it may be safely inferred that " the mean height of the barometer at the level of the sea being the same in every part of the globe...
Page 110 - This last quantity was declared in 1799 to be the length of the legal metre, and vrai et deftnitif, and is the length of Lenoir's platina standard. Later and more extensive measurements in various parts of the globe, however, seem to indicate that this quantity is somewhat too small. The latest and most exact results we now possess, combined and computed by Bessel, would make the quarter of the meridian 10,000,856 metres, and the me"tre = 443-29979 Paris lines. Schmidt's computation would make it...
Page 110 - Schmidt's computation would make it 443.29977 lines, and both numbers are confirmed by Airy's results. The legal metre is thus, in fact, as Dove remarks, a legalized part of .the toise du Perou, and this last remains the primitive standard. But it must be added that a natural standard, in the absolute sense of the word, is a Utopian one, which ever-changing Nature never will give us. The metre is, for all practical purposes, what it was intended to be, a natural standard ; though it must be confessed...