Page images
PDF
EPUB

air from the valleys. Thin cirrus clouds floated above the hill all day, and detached masses of fog were in the valleys. The next day the hilltop was enveloped in mist, and thick cumulus clouds were observed over Fort William with a smaller hourly variation both of temperature and water-vapour.

Mr. Marr continued the work at Fort William at Christmas, and Mr. Herbertson in May, the latter having carried on the experiments in the drier air of Montpellier during the early months of this year. These data have served to extend the curves drawn from the figures already obtained, the Montpellier results being found to agree well with those made at Fort William where they overlapped.

It is Mr. Herbertson's intention to continue these investigations in the coming autumn and winter, more special attention being then given to secure an increased number of simultaneous high and low determinations of water-vapour.

The inquiry into the hourly variation of pressure and temperature at the observatories during days of clear weather on the one hand, and days of fog or mist throughout on the other, has been prosecuted during the year. On completing the hourly variations of pressure during each of these two distinct types of weather at the Low Level Observatory at Fort William on the same days at the top of the mountain, it was seen that substantially the same sets of curves obtained in both situations. In particular at both places the same extraordinarily high pressure from about 6 P.M. to 2 A.M. occurs during days of fog or mist, or completely clouded days, thus demonstrating the important role played by the aqueous vapour of the atmosphere in the diurnal meteorological changes. The point was considered to be of such importance as to warrant the extension of the inquiry to another place where the climate, as regards moisture, resembles in some degree that of Fort William. Trieste, at the head of the Adriatic Sea, was selected for examination, particularly since the hourly values for pressure and sunshine are published for this place. The results for the three observatories are given in Tables III. to VIII. of this Report. The times over which the inquiry extends are three years, from August 1890 to July 1892 for the Ben Nevis Observatories, and the three years 1888 to 1890 for Trieste. The results have been 'bloxamed,' as explained in our last Report (p. 284).

The results of the investigation, so far as it has been carried, are, broadly stated, these :-During fine cloudless weather the hourly curves. of the three places are virtually congruent with their curves for the whole of the observations, clear and clouded alike, except that the diurnal phases of maxima and minima are more strongly pronounced, and the evening maximum is continued for a shorter period. During foggy and clouded weather each of the three places shows in the colder months: of the year the ordinary double maxima and minima of pressure fairly well marked. It is quite otherwise in the warmer months, when at the Ben Nevis Observatories the morning maximum is virtually obliterated, and Trieste very greatly reduced. It is, however, the evening maximum which shows the most surprising results. This is at all seasons at the low-level stations, but in the warmer months it is the outstanding feature of the curves. For May, June, and July the mean at the top is 0.018 inch, at Fort William 0·023 inch, and at Trieste also 0.023 inch. In these months the maximum of this phase of the barometric curve occurred either at midnight or shortly before it.

The temperature curves for the Ben Nevis Observatory have also been 1894.

1

calculated, with the result that on clear days the diurnal range of temperature is only very slightly in excess of that of foggy days. But in summer the difference between the mean coldest and warmest hour is 1o•1; but on clear days the difference is 2°-9, or nearly three times greater.

The further prosecution of this inquiry and examination of the cyclones and anti-cyclones of North-Western Europe will engage the attention of your Committee next year, when a large portion of the time of Dr. Buchan and Mr. Omond will be given to this work.

TABLE III.-Showing at the Ben Nevis Observatory the Mean Hourly Variation of Pressure, in thousandths of an inch, during clear days. The minus sign means under the average.

Hour

Jan. Feb. Mar. April May June July Aug. Sept. Oct. Nov. Dec. Year

[merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

TABLE IV. Showing at the Ben Nevis Observatory the Mean Hourly Variation of Pressure, in thousandths of an inch, during days of fog or mist. The minus sign shows the means under the average.

Hour

Jan. Feb. Mar. April May June July Aug. Sept. Oct. Nov.

Dec. Year

[merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][ocr errors][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][ocr errors][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

TABLE V.-Showing at Fort William Observatory the Mean Hourly Variation of Pressure, in thousandths of an inch, during clear days. The minus sign shows means under the average.

Hour

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Year

[merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

TABLE VI.-Showing at Fort William Observatory the Mean Hourly Variation of Pressure, in thousandths of an inch, during days of fog or mist. The minus sign shows means under the average.

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

TABLE VII.-Showing at Trieste the Mean Hourly Variation of Pressure, in thousandths of an inch, during clear days. The minus sign shows means under the average.

Hour

Jan. Feb. Mar. April May June July Aug. Sept., Oct. Nov. Dec. Year

[merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][subsumed][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

TABLE VIII.-Showing at Trieste the Mean Hourly Variation of Pressure, in thousandths of an inch, during completely clouded days. The minus sign indicates means above the average.

124444789

Hour

10

11

Noon

1 PM.

Jan. Feb. Mar. April May June July Aug. Sept. Oct. Nov. Dec. Year

[merged small][merged small][merged small][ocr errors]

1 A.M.

[ocr errors]

+7

+8

+8 +10

+10

+ 4

[ocr errors]

+6 + 8

- 2

-6

- 9

-12

+ 5
- 2 - 7
-10
-16

+6

+12

+1

+6

-13
-19

- 7

[blocks in formation]
[blocks in formation]

- 0 - 9

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

Experiments for Improving the Construction of Practical Standards for Electrical Measurements.-Report of the Committee, consisting of Professor CAREY FOSTER (Chairman), Lord KELVIN, Professors AYRTON, J. PERRY, W. G. ADAMS, and Lord RAYLEIGH, Drs. 0. J. LODGE, JOHN HOPKINSON, and A. MUIRHEAD, Messrs. W. H. PREECE and HERBERT TAYLOR, Professor J. D. EVERETT, Professor A. SCHUSTER, Dr. J. A. FLEMING, Professors G. F. FITZGERALD, G. CHRYSTAL, and J. J. THOMSON, Messrs. R. T. GLAZEBROOK (Secretary), and W. N. SHAW, Rev. T. C. FITZPATRICK, Dr. J. T. BOTTOMLEY, Professor J. VIRIAMU JONES, Dr. G. JOHNSTONE STONEY, Professor S. P. THOMPSON, and Mr. G. FORBES.

APPENDIX

I. Report of the American Delegates at the Chicago Conference to the
Secretary of State at Washington

[ocr errors]

II. Experiments on the Value of the Ohm. By J. VIRIAMU JONES
III. Comparison of the Standards employed by Professor Jones with the
Standards of the Association. By R. T. GLAZEBROOK

PAGE

119

[ocr errors]

123

[ocr errors]

128

Trade with

130

V.

E. O. WALKER

131

[ocr errors]

VI.

On the Specific Resistance of Copper and of Silver. By Rev. T. C.
FITZPATRICK

131

IV. Comparison of Some of the Standards of the Board of
those of the Association. By J. RENNIE
Values of Certain Coils belonging to the Indian Government. By

VII. Final Report of the Electrical Standards Committee of the Board of
Trade, and Order in Council regarding Standards for Electrical
Measurements

.

136

THE work of testing resistance coils at the Cavendish Laboratory has been continued. A table of the coils tested is given.

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]
« PreviousContinue »