A Treatise on Meteorological Instruments Part 20

"The Germans indicate inches by putting two accents after the number; lines, by putting three accents; 27" 3'''85, means 27 inches 3 lines 85 hundredths of a line; more frequently, they give the height in lines, and the preceding number becomes 327'''85."--_Kaemtz._

3. _Rule for finding Diameter of Bore of a Barometer Tube._

"If the maker has not taken care to measure the interior diameter directly, it may be deduced from the exterior diameter. The exterior diameter is first measured by calipers, and, by deducting from this diameter 01 of an inch for tubes from 3 to 5 of an inch in external diameter, we have an approximation to the interior diameter of the tube."--_Kaemtz._

4. WIND SCALES.

Sea Scale. Wind. Land Scale.

---------- ----- ----------- 0 to 3 = Light = 0 to 1 3 " 5 = Moderate = 1 " 2 5 " 7 = Fresh = 2 " 3 7 " 8 = Strong = 3 " 4 8 " 10 = Heavy = 4 " 5 10 " 12 = Violent = 5 " 6

Pressure in Velocity in Pounds (Land Scale). Miles (Avoirdupois) (Hourly).

------------- --------- ----------- 1/2 = 1 = 10 5 = 2 = 32 10 = 3 = 45 21 = 4 = 65 26 = 5 = 72 32 = 6 = 80

5. Letters to Denote the State of the Weather.

_b_ denotes blue sky, whether with clear or hazy atmosphere.

_c_ " cloudy, that is detached opening clouds.

_d_ " drizzling rain.

_f_ " fog.

_h_ " hail.

_l_ " lightning.

_m_ " misty, or hazy so as to interrupt the view.

_o_ " overcast, gloomy, dull.

_p_ " pa.s.sing showers.

_q_ " squally.

_r_ " rain.

_s_ " snow.

_t_ " thunder.

_u_ " ugly, threatening appearance of sky.

_v_ " unusual visibility of distant objects.

_w_ " wet, that is dew.

A letter repeated denotes much, as _r r_, heavy rain; _f f_, dense fog; and a figure attached denotes duration in hours, as 14 _r_, 14 hours rain.

By the combination of these letters, all the ordinary phenomena of the weather may be recorded with certainty and brevity.

EXAMPLES.--_b c_, blue sky with less proportion of cloud. 2 _r r l l t_, heavy rain for two hours, with much lightning, and some thunder.

The above methods of recording the force of wind and state of weather were originally proposed by Admiral Sir Francis Beaufort. They are now in general use at sea, and by many observers on land.

6. Table of Expansion by Heat from 32 to 212 F.

Platinum 00008842 of the length.

Gla.s.s, Flint 00008117 "

" with Lead 00008622 "

Bra.s.s 00018708 "

Mercury 00180180 "

Water 00433200, from 39 to 212 Alcohol 01100 " 32 to 174 Nitric Acid 01100 Sulphuric Acid 00600

7. Table of Specific Gravity of Bodies at 32 F. except water, which is taken at 394.

Water 1000 Alcohol, pure 0791 " proof 0916 Mercury 13596 Gla.s.s 3 to 27 Bra.s.s 78 to 854 Platinum 21 to 2200

Weight of a cubic foot of water, at the temperature of comparison, 62425 lbs. avoirdupois.

The pound avoirdupois contains 7,000 grains.

Air is 81367 times lighter than water.

The linear expansions are the mean values of the results of various experimentalists. The specific gravities are as given in Professor Rankine's _Applied Mechanics_.

8. Important Temperatures. Under the circ.u.mstances of--

Water boiling at 212 Mercury boils at 660 Sulphuric Acid " 590 Oil of Turpentine " 560 Nitric Acid " 242 Alcohol " 174 A Saturated Solution of Salt " 218 Vital Heat 96 Olive Oil begins to solidify 36 Fresh Water freezes 32 Sea Water freezes 28 Mercury freezes -39

9. TABLE OF METEOROLOGICAL ELEMENTS, FORMING EXPONENTS OF THE CLIMATE OF LONDON.

--------------------------------------------------------------------+ 1841 Mean Height of Barometer, reduced to 32 F., at the mean to sea-level. 1861. +-------------------------------------------------- Mean Monthly Range of Barometer. Months. +--------------------------------------------- Mean of all the Highest Temperatures. +---------------------------------------- Mean of all the Lowest Temperatures. +----------------------------------- Mean Temperature. +------------------------------ Mean Temperature of Dew-point. +------------------------- Mean Degree of Humidity. +---------------------- Mean Number of Rainy Days. +------------------ Average Rainfall. +------------- Average Amount of Cloud (10= overcast). +--------- Prevalent Winds. ---------+-------+----+----+----+----+----+--+---+----+---+---------+ Inches. In. In. ---------+-------+----+----+----+----+----+--+---+----+---+---------+ January 29932 144 432 337 383 354 89 11 18 77 W. to N. February 29962 122 447 332 384 344 85 10 16 74 S. to W. March 29967 123 500 353 417 364 82 10 15 66 N. to E. April 29907 106 568 386 463 399 79 11 18 61 N. to E. May 29931 102 644 442 528 455 76 11 21 61 S. to W. June 29960 089 712 502 592 508 74 11 19 61 W. to N. July 29970 079 738 532 619 539 76 11 27 69 W. to N. August 29954 097 728 534 613 541 77 11 24 65 W. to N. September 29997 095 674 489 569 511 81 12 24 59 S. to W. October 29860 133 583 437 502 460 87 13 28 69 S. to W. November 29929 153 493 377 434 401 89 12 24 72 S.W. December 29979 152 450 355 401 369 89 12 19 74 W. ---------+-------+----+----+----+----+----+--+---+----+---+---------+ Year 29946 116 580 423 492 437 82 133 253 67 -- ---------+-------+----+----+----+----+----+--+---+----+---+---------+ 1 2 3 4 5 6 7 8 9 10 11 ---------------------------------------------------------------------

+-----------------------------------------------------+ Sun above the Horizon on Middle Day. +--------------------------------------------- REMARKS. ---------+-------+--------------------------------------------- Hours. ---------+-------+--------------------------------------------- January 8-1/2 The majority of the nights are frosty. February 10 10 frosty nights on the average. March 12 12 ditto ditto ditto. Strong winds. April 14 6 ditto ditto ditto. May 15-1/2 Very rarely frost. June 16-1/2 Sun attains greatest North Declination, 21st. July 16 August 14-1/2 September 12-1/2 October 10-1/2 A few frosty nights. Heavy gales. November 9 11 nights frosty. December 8 Sun attains greatest South Declination, 21st. ---------+-------+--------------------------------------------- Year -- ---------+-------+--------------------------------------------- 12 13 ---------------------------------------------------------------+

In the above Table, columns 1 to 10 are results obtained at the Royal Observatory, Greenwich, by J. Glaisher, Esq., F.R.S. The data contained in columns 2 and 10, are deduced from observations extending over the years 1841 to 1855 inclusive, and are copied from Edward Hughes' _Third Reading Book_; the other columns are results of observations made during the twenty years ending 1861. The rest of the information is from Luke Howard's _Climate of London_.

These valuable data indicate the characteristics of the weather in each month in the suburbs of London, and will be found tolerably accurate as indications of weather, and serviceable as standards for comparisons of observed results, at most places in England.

STANDARD WORKS ON METEOROLOGY

SUPPLIED BY NEGRETTI & ZAMBRA.

THE WEATHER BOOK: A MANUAL OF PRACTICAL METEOROLOGY.

By Vice-Admiral FITZROY, F.R.S., M.I.F., &c.

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THE LAW OF STORMS, By H. W. DOVE, F.R.S.

Translated by R. H. SCOTT, M.A.

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