Himalayan Journals
Volume II

## Appendix

J.
ON THE MEASUREMENT OF ALTITUDES BY THE BOILING-POINT THERMOMETER.

The use of the boiling-point thermometer for the determination of elevations in mountainous countries appearing to me to be much underrated, I have collected the observations which I was enabled to take, and compared their results with barometrical ones.

I had always three boiling-point thermometers in use, and for several months five; the instruments were constructed by Newman, Dollond, Troughton, and Simms, and Jones, and though all in one sense good instruments, differed much from one another, and from the truth. Mr. Welsh has had the kindness to compare the three best instruments with the standards at the Kew Observatory at various temperatures between 180° and the boiling-point; from which comparison it appears, that an error of l·5° may be found at some parts of the scale of instruments most confidently vouched for by admirable makers. Dollond’s thermometer, which Dr. Thomson had used throughout his extensive west Tibetan journeys, deviated but little from the truth at all ordinary temperatures. All were so far good, that the errors, which were almost entirely attributable to carelessness in the adjustments, were constant, or increased at a constant ratio throughout all parts of the scale; so that the results of the different instruments have, after correction, proved strictly comparable.

The kettle used was a copper one, supplied by Newman, with free escape for the steam; it answered perfectly for all but very high elevations indeed, where, from the water boiling at very low temperatures, the metal of the kettle, and consequently of the thermometer, often got heated above the temperature of the boiling water.

I found that no confidence could be placed in observations taken at great elevations, by plunging the thermometer in open vessels of boiling water, however large or deep, the abstraction of heat from the surface being so rapid, that the water, though boiling below, and hence bubbling above, is not uniformly of the same temperature throughout.

In the Himalaya I invariably used distilled, or snow or rain-water;

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but often as I have tried common river-water for comparison, I never found that it made any difference in the temperature of the boiling-point. Even the mineral-spring water at Yeumtong, and the detritus-charged glacial streams, gave no difference, and I am hence satisfied that no objection can be urged against river waters of ordinary purity.

On several occasions I found anomalous rises and falls in the column of mercury, for which I could not account, except theoretically, by assuming breaks in the column, which I failed to detect on lifting the instrument out of the water; at other times, I observed that the column remained for several minutes stationary, below the true temperature of the boiling water, and then suddenly rose to it. These are no doubt instrumental defects, which I only mention as being sources of error against which the observer must be on the watch: they can only be guarded against by the use of two instruments.

With regard to the formula employed for deducing the altitude from a boiling-point observation, the same corrections are to a great extent necessary as with barometric observations: if no account is taken of the probable state of atmospheric pressure at the level of the sea at or near the place of observation, for the hour of the day and month of the year, or for the latitude, it is obvious that errors of 600 to 1000 feet may be accumulated. I have elsewhere stated that the pressure at Calcutta varies nearly one inch (1000 feet), between July and January; that the daily tide amounts to one-tenth of an inch (=100 feet); that the multiplier for temperature is too great in the hot season and too small in the cold; and I have experimentally proved that more accuracy is to be obtained in measuring heights in Sikkim, by assuming the observed Calcutta pressure and temperature to accord with that of the level of the sea in the latitude of Sikkim, than by employing a theoretical pressure and temperature for the lower station.

In the following observations, the tables I used were those printed by Lieutenant-Colonel Boileau for the East India Company’s Magnetic Observatory at Simla, which are based upon Regnault’s Table of the ‘Elastic Force of Vapour.’ The mean height of the barometrical column is assumed (from Bessel’s formula) to

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be 29·924 at temp. 32°, in lat. 45°, which, differing only ·002 from the barometric height corresponding to 212° Fahrenheit, as determined experimentally by Regnault, gives 29·921 as the pressure corresponding to 212° at the level of the sea.

The approximate height in feet corresponding to each degree of the boiling-point, is derived from Oltmann’s tables. The multipliers for the mean temperature of the strata of atmosphere passed through, are computed for every degree Fahrenheit, by the formula for expansion usually employed, and given in Baily’s Astronomical Tables and Biot’s Astronomie Physique.

For practical purposes it may be assumed that the traveller, in countries where boiling-point observations are most desired, has never the advantage of a contemporaneous boiling-point observation at a lower station. The approximate difference in height is hence, in most cases, deduced from the assumption, that the boiling-point temperature at the level of the sea, at the place of observation, is 212°, and that the corresponding temperature of the air at the level of the sea is hotter by one degree for every 330 feet of difference in elevation. As, however, the temperature of boiling water at the level of the sea varies at Calcutta between July and January almost from 210·7° to 212·6°, I always took the Calcutta barometer observation at the day and hour of my boiling-point observation, and corrected my approximate height by as many feet as correspond to the difference between the observed height of the barometer at Calcutta and 29·921; this correction was almost invariably (always normally) subtractive in the summer, often amounting to upwards of 400 feet: it was additive in winter, and towards the equinoxes it was very trifling.

For practical purposes I found it sufficient to assume the Calcutta temperature of the air at the day and hour of observation to be that of the level of the sea at the place of observation, and to take out the multiplier, from the mean of this and of the temperature at the upper station. As, however, 330 feet is a near approach to what I have shown (Appendix I) to be the mean equivalent of 1° for all elevations between 6000 and 18,000 feet; and as the majority of my observations were taken between these elevations, it results that the mean of all the multipliers employed in Sikkim for forty-four

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observations amounts to 65·1° Fahrenheit, using the Calcutta and upper station observations, and 65·3° on the assumption of a fall of 1° for every 330 feet. To show, however, how great an error may accrue in individual cases from using the formula of 1° to 330, I may mention that on one occasion, being at an elevation of 12,000 feet, with a temperature of the air of 70°, the error amounted to upwards of 220 feet, and as the same temperature may be recorded at much greater elevations, it follows that in such cases the formula should not be employed without modification.

A multitude of smaller errors, arising from anomalies in the distribution of temperature, will be apparent on consulting my observations on the temperature at various elevations in Sikkim; practically these are unavoidable. I have also calculated all my observations according to Professor J. Forbes’s formula of 1° difference of temperature of boiling-water, being the equivalent of 550 feet at all elevations. (See Ed. Phil. Trans., vol xv. p. 405.) The formula is certainly not applicable to the Sikkim Himalaya; on the contrary, my observations show that the formula employed for Boileau’s tables gives at all ordinary elevations so very close an approach to accuracy on the mean of many observations, that no material improvement in its construction is to be anticipated.

At elevations below 4000 feet, elevations calculated from the boiling-point are not to be depended on; and Dr. Thomson remarked the same in north-west India: above 17,000 feet also the observations are hazardous, except good shelter and a very steady fire is obtainable, owing to the heating of the metal above that of the water. At all other elevations a mean error of 100 feet is on the average what is to be expected in ordinary cases. For the elevation of great mountain masses, and continuously elevated areas, I conceive that the results are as good as barometrical ones; for the general purposes of botanical geography, the boiling-point thermometer supersedes the barometer in point of practical utility, for under every advantage, the transport of a glass tube full of mercury, nearly three feet long, and cased in metal, is a great drawback to the unrestrained motion of the traveller.

In the Khasia mountains I found, from the mean of twelve stations and twenty-three observations, the multiplier as derived from the

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mean of the temperature at the upper station and at Calcutta, to be 75.2°, and as deduced from the formula to be 73·1°. Here, however, the equivalent in feet for 1° temp. is in summer very high, being 1°=385 feet. (See Appendix I.) The mean of all the elevations worked by the boiling-point is upwards of 140 feet below those worked by the barometer.

The following observations are selected as having at the time been considered trustworthy, owing to the care with which they were taken, their repetition in several cases, and the presumed accuracy of the barometrical or trigonometrical elevation with which they are compared. A small correction for the humidity of the air might have been introduced with advantage, but as in most barometrical observations, the calculations proceed on the assumption that the column of air is in a mean state of saturation; as the climate of the upper station was always very moist, and as most of the observations were taken during the rains, this correction would be always additive, and would never exceed sixty feet.

It must be borne in mind that the comparative results given below afford by no means a fair idea of the accuracy to be obtained by the boiling-point. Some of the differences in elevation are probably due to the barometer. In other cases I may have read off the scale wrong, for however simple it seems to read off an instrument, those practically acquainted with their use know well how some errors almost become chronic, how with a certain familiar instrument the chance of error is very great at one particular part of the scale, and how confusing it is to read off through steam alternately from several instruments whose scales are of different dimensions, are differently divided, and differently lettered; such causes of error are constitutional in individual observers. Again, these observations are selected without any reference to other considerations but what I have stated above; the worst have been put in with the best. Had I been dependent on the boiling-point for determining my elevations, I should have observed it oftener, or at stated periods whenever in camp, worked the greater elevations from the intermediate ones, as well as from Calcutta, and resorted to every system of interpolation. Even the following observations would be amended considerably were I to have deduced the elevation by

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observations of the boiling-point at my camp, and added the height of my camp, either from the boiling-point observations there, or by barometer, but I thought it better to select the most independent method of observation, and to make the level of the sea at Calcutta the only datum for a lower station.

SERIES I.—Sikkim Observations.

Place | Month | Elevation by Barom. or Trigonom. | Temp. B.P. | Air | Elevation by B.P. | Error
Great Rungeet river Bhomsong Guard House, Great Rungeet Choongtam Dengha Mr. Muller’s (Dorjiling) Dr. Campbell’s (Dorjiling) Mr. Hodgson’s (Dorjiling) Sinchul Lachoong Lamteng Zemu Samdong Mainom Junction of Zemu & Thlonok Tallum Yeumtong Zemu river Tungu Jongri Zemu river Lachee-pia Momay Palung Kongra Lama Snow-bed above Yeumtong Tunkra pass Yeumtso Donkia Mountain above Momay Sebolah pass Kinchinjow Donkia Mountain Donkia Mountain Bhomtso Donkia pass | Feb. Dec. Apr. Aug. Aug. Feb. Apr. Feb. Jan. Aug. Aug. July Dec. July July Sept. June July/Oct. Jan. June Aug. Sept. Oct. July Sept. Aug. Oct. Sept. Sept. Sept. Sept. Sept. Sept. Oct. Sept. | (feet) B. 818 1,544 1,864 5,268 6,368 Tr. 6,925 6,932 B. 7,429 Tr. 8,607 B. 8,712 8,884 8,976 Tr. 10,702 B. 10,846 11,482 11,919 12,070 12,751 13,194 13,281 15,262 15,362 15,620 15,694 15,985 16,083 16,808 16,978 17,394 17,585 17,624 18,510 18,307 18,450 18,466 | 210·7 210·2 208·1 202·6 200·6 199·4 200·1 199·4 197·0 196·4 196·3 196·1 193·4 193·6 191·8 191·3 190·4 189·7 188·8 188·5 186·0 186·1 185·4 184·1 184·6 164·1 183·1 182·4 181·9 181·9 181·0 180·6 179·9 181·2 181·2 | 56·3 58·0 72·7 65·0 68·0 41·3 59·5 47·6 41·7 54·6 77·0 58·6 38·0 52·0 54·6 52·2 48·5 43·4 26·0 47·0 42·8 48·6 45·8 41·5 44·5 39·0 15·0 41·0 47·8 46·5 47·5 37·1 38·8 52·0 45·5 | (feet) 904 1,321 2,049 5,175 6,246 7,122 6,745 7,318 8,529 8,777 8,937 8,916 10,516 10,872 11,451 11,887 12,139 12,696 13,151 13,360 14,912 14,960 15,437 16,041 15,816 16,317 16,279 17,049 17,470 17,517 18,026 18,143 18,597 18,305 17,866 | (feet) + 86 – 223 + 185 – 93 – 122 + 197 – 187 – 111 – 78 + 65 + 53 – 60 – 186 + 26 – 31 – 32 + 69 – 55 – 43 + 79 – 350 – 402 – 183 + 347 – 169 + 54 – 529 + 71 + 76 – 68 + 402 – 367 + 290 – 145 – 600
| Mean |  |  |  |  | – 58

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SERIES II.—Khasia Observations.

Place | Month | Elevation by Barometer | Temp. B.P. | Air | Elevation by B.P. | Diff.
Churra Amwee Nurtiung Nunklow Kala-panee Myrung Syong Moflong Chillong | June September October July June, July, Sept., Oct. July July July, Aug., Oct., Nov. November | (feet) 4,069 4,105 4,178 4,688 5,302 5,647 5,725 6,062 6,662 | 204·4 205·1 205·0 203·9 202·2 201·9 201·8 201·4 201·2 | 70·3 67·7 70·0 69·8 65·8 69·4 70·8 64·8 62·8 | (feet) 4,036 4,041 4,071 4,333 5,202 5,559 5,632 5,973 6,308 | (feet) – 33 – 64 – 107 – 355 – 100 – 88 – 93 – 89 – 354
| Mean | 5,160 |  |  | 5·016 | – 143

K.
ACTINOMETER OBSERVATIONS.

The few actinometer observations which I was enabled to record, were made with two of these instruments constructed by Barrow, and had the bulbs of their thermometers plunged into the fluid of the chamber. They were taken with the greatest care, in conformity with all the rules laid down in the “Admiralty Guide,” and may, I think, be depended upon. In the Sikkim Himalaya, a cloudless day, and one admitting of more than a few hours’ consecutive observations, never occurs—a day fit for any observation at all is very, rare indeed. I may mention here that a small stock of ammonia-sulphate of copper in crystals should be supplied with this instrument, also a wire and brush for cleaning, and a bottle with liquid ammonia: all of which might be packed in the box. Active 6.568. Time always mean.

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Jillapahar, Dorjiling, Elev. 7,430 feet, Lat. 27° 3′ N., Long. 88° 13′ E.

A.—APRIL 19TH, 1850. Watch slow 1′ 15″ mean time.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. | Black Bulb |
8.00 to 8.13 a.m. 8.15 to 8.28 a.m. 9.00 to 9.13 a.m. 10.00 to 10.13 a.m. 11.00 to 11.13 a.m. Noon to 12.13 p.m. 1.00 to 1.13 p.m. 2.00 to 2.13 p.m. | 11·1 15·0 17·7 19·1 19·0 18·8 17·2 17·4 | 65·5 69·5 71·5 72·5 75·0 75·0 73·3 74·0 | 9·9900 12·2645 14·5140 15·4710 14·9150 12·7600 13·8976 13·8330 | 22·960 22·948 22·947 22·946 22·944 22·939 22·914 | 53·5 56·0 57·0 58·5 60·3 59·4 60·3 | 33·8 37·2 39·7 38·2 44·8 40·7 44·1 | 19·7 18·8 17·3 20·3 15·5 18·7 16·2 | ·505 ·513 ·550 ·500 ·592 ·546 ·577 | 88·0 111·5 110·0 121·0 125·0 120·0 122·0 108·0 | Day unexceptional, wind S.W., after 10 a.m. squally. Dense haze over snowy mountains.

B.—APRIL 20TH.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. | Black Bulb |
8.0 to 8.30 a.m. 9.0 to 9.13 a.m. 10.0 to 10.13 a.m. | 11·8 17·8 18·8 | 64·0 73·3 65·0 | 10·9150 14·2750 14·7580 | 22·969 22·974 22·985 | 54·2 56·2 57·0 | 43·4 44·1 42·5 | 10·8 12·1 14·5 | ·691 ·662 ·609 | 74·0 92·0 92·0 | Dense haze, S.E. wind, cloudless sky.

Superintendent's House, Dorjiling, Elev. 6,932 feet.

C.—APRIL 21ST. Watch slow 1′ mean time.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. | Black Bulb |
8.35 to 8.48 a.m. 9.07 to 9.20 a.m. 10.00 to 10.13 a.m. 11.00 to 11.13 a.m. | 17·3 20·9 23·9 24·4 | 65·0 72·7 77·3 81·0 | 15·7084 16·8872 18·3791 17·8864 | 23·447 | 56·4 63·8 60·8 | 47·6 49·9 49·2 | 8·8 13·9 11·6 | ·741 ·628 ·677 | 97.0 100·0 109·0 107·5 | Day very fine, snowy mts. in dull red haze, wind S.E. faint.

Rampore Bauleah (Ganges). Elev. 130 feet, Lat. 24° 24′ N., Long. 88° 40′ E.

MAY 17TH, 1850. Watch slow 15″ mean time.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. | Black Bulb |
7.51 to 8.13 a.m. 9.03 to 9.17 a.m. 9.20 to 9.33 a.m. 11.15 to 11.28 a.m. 11.32 to 11.45 a.m. 1.20 to 1.33 p.m. 1.40 to 1.53 p.m. | 13·0 19·5 21·2 21·1 16·5 21·6 21·4 | 88·0 96·0 107·0 105·0 108·7 108·5 113·7 | 8·8790 12·5190 12·7836 12·8499 9·8770 12·9348 12·4976 | 29·698 29·615 29·620 | 87·5 92·0 92·3 98·5 98·3 104·5 105·8 | 80·1 81·2 80·2 74·8 74·3 76·7 72·2 | 7·4 10·8 12·1 23·7 24·0 27·8 33·6 | ·793 ·715 ·687 ·478 ·475 ·425 ·355 | 91·0 83·8 132·0 98·5 142·0 144·0 134·0 | S.E. wind, very hazy to west, sky pale blue. Wind west, rising.

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Churra, Khasia Mountains. Elev. 4,225 feet, Lat. 25° 15′ N., Long. 91° 47′ E.

A.—NOVEMBER 4TH, 1850. Watch slow 7′ mean time.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. | Black Bulb |
6.20 to 6.30 a.m. 6.32 to 6.42 a.m. 7.55 to 8.05 a.m. 8.08 to 8.18 a.m. 8.20 to 8.30 a.m. | 5·0 7·4 20·0 21·0 24·2 | 63·7 65·4 77·5 82·0 85·8 | 4·6400 6·6896 15·2400 15·2040 16·8432 | 25·781 | 57·8 59·0 63·5 64·4 64·8 | 53·1 54·8 56·9 57·3 59·5 | 4·7 4·2 6·6 7·1 5·3 | ·850 ·870 ·806 ·790 ·837 | 75·0 83·0 108·0 106·5 113·5 | Sky faint blue, cloudless, wind S.W., clouding.

B.—NOVEMBER 5TH. Watch slow 7′ mean time.

Hour | Act. | Temp. Act. | Act. reduced | Air | D.P. | Diff. | Sat. | Black Bulb |
6.39 to 6.49 a.m. 6.51 to 7.01 a.m. 7.56 to 8.06 a.m. 8.08 to 8.21 a.m. 9.26 to 9.36 a.m. 9.37 to 9.47 a.m. 10.57 to 11.07 a.m. | 11·2 13·4 18·4 20·4 23·8 25·1 29·0 | 70·2 72·8 73·2 77·7 79·5 84·0 89·5 | 9·3408 10·8138 15·0161 15·4836 17·8072 17·7959 19·5460 | 59·4 60·5 61·7 63·3 66·7 | 57·6 57·8 57·7 58·7 60·8 | 1·8 2·7 4·0 4·6 5·9 | ·940 ·918 ·875 ·860 8·28 | 126·0 | Wind S.W., clouds rise and disperse. Sky pale.

C.—NOVEMBER 6TH. Watch slow 7′ mean time.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. | Black Bulb |
6.05 to 6.18 a.m. 6.22 to 6.35 a.m. 6.38 to 6.51 a.m. 8.27 to 8.37 a.m. 8.39 to 8.52 a.m. | 2·6 6·5 9·6 21·7 23·0 | 62·0 63·5 66·7 78·8 81·7 | 2·4986 6·0710 8·5152 16·2750 19·4750 | 25·781 | 56·5 57·0 61·0 64·2 64·5 | 54·5 55·1 57·4 59·3 59·4 | 2·0 1·9 3·6 4·9 5·1 | ·935 ·935 ·888 ·855 ·847 | 100·0 105·0 | Sunrise, 6, pale yellow red, cloudless. Cirrhus below.

D.—NOVEMBER 14TH, 1850.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. | Black Bulb |
6.12 to 6.22 a.m. 6.24 to 6.37 a.m. 7.13 to 7.23 a.m. 7.24 to 7.34 a.m. 8.34 to 8.44 a.m. 8.47 to 9.00 a.m. 9.53 to 10.03 a.m. 10.04 to 10.17 a.m. 11.24 to 11.31 a.m. | 2·9 6·1 12·4 14·7 19·9 21·7 23·5 25·3 33·3 | 60·6 66·0 70·8 76·0 82·8 88·8 86·6 89·5 111·5 | 3·5988 5·4472 10·2672 11·4025 14·2653 14·7343 16·2620 17·0775 20·7014 | 25·783 25·832 25·819 | 51·5 52·7 56·5 57·8 59·8 60·5 67·2 67·0 64·6 | 49·4 50·3 52·3 53·1 50·8 51·6 61·6 58·8 59·0 | 2·1 2·4 4·2 4·7 9·0 8·9 5·6 8·2 5·6 | ·930 ·925 ·900 ·855 ·742 ·730 ·832 ·778 ·832 | 98·0 104·0 117·0 121·0 127·0 133·0 130·0 | Thick cumulus low on plains. Sunrise yellow red. Cloudless. Clouds rise.

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E.—NOVEMBER 15TH, 1850.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. |
9.53 to 10.06 a.m. 10.50 to 11.03 a.m. 11.31 to 11.44 a.m. 12.33 to 12.46 p.m. 1.07 to 1.21 p.m. 2.47 to 3.00 p.m. 3.48 to 4.00 p.m. 4.03 to 4.16 p.m. | 25·8 26·1 28·5 30·9 29·1 21·1 16·7 16·2 | 78·0 80·5 84·0 91·5 90·5 75·0 73·0 75·0 | 17·5306 19·1835 20·2065 20·4267 20·4388 16·5635 13·4435 12·7170 | 25·854 25·844 25·808 25·803 | 63·0 64·0 65·3 65·8 67·0 67·2 62·0 61·5 | 55·3 52·8 51·9 51·2 49·6 56·6 50·8 50·5 | 8·7 11·2 13·4 14·6 17·4 10·6 11·2 11·0 | ·772 ·690 ·638 ·620 ·560 ·708 ·690 ·692 | Sky cloudless. Wind N.E.

Silchar (Cachar). Elev. 116 feet, Lat. 24° 30′ N., Long. 93° E. (approximate)

NOVEMBER 26TH, 1850. Watch slow 13′ 39″ mean time.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. |
9.11 to 9.24 a.m. 9.34 to 9.41 a.m. 9.50 to 9.57 a.m. 10.07 to 10.14 a.m. 11.03 to 11.16 a.m. Noon to 12.03 p.m. 12.58 to 1.11 p.m. 2.51 to 3.04 p.m. 3.55 to 4.08 p.m. 4.09 to 4.22 p.m. 4.23 to 4.36 p.m. | 19·4 22·7 25·3 26·5 26·3 26·4 27·6 23·0 17·6 15·5 12·0 | 69·0 81·0 87·5 91·5 89·0 90·0 94·0 93·0 91·5 93·5 93·7 | 16·4706 16·5937 17·3558 17·5695 17·5251 17·8144 17·9676 15·0880 11·6688 11·0215 7·8360 | 29·999 29·967 29·892 29·881 | 66·3 68·7 70·3 73·2 74·5 76·8 78·5 79·5 79·4 78·5 | 63·5 61·5 62·7 60·3 61·7 60·3 62·1 57·0 62·1 62·1 | 2·8 7·2 7·6 12·9 12·8 16·5 16·4 22·5 17·3 16·4 | ·860 ·788 ·780 ·657 ·658 ·586 ·588 ·480 ·570 ·588 | Dense fog till 7.30 a.m. Wind north. Clear. Wind N.E. Light cirrhus low. Streaks of cirrhus aloft. Sun sets in hazy cirrhus.

Chittagong, Elev. 200 feet, Lat. 22° 20′ N., Long. 91° 55′ E.

A.—DECEMBER 31ST, 1850. Watch slow 3′ 45″ mean time.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. | Black Bulb |
7.39 to 7.52 a.m. 8.40 to 8.53 a.m. 9.04 to 9.08 a.m. 9.52 to 9.56 a.m. 10.02 to 10.06 a.m. 11.16 to 11.29 a.m. 11.52 to 11.56 a.m. 1.38 to 1.41 p.m. 1.47 to 1.51 p.m. 3.10 to 3.17 p.m. 3.18 to 3.25 p.m. | 10·0 21·3 23·2 24·3 25·1 24·3 26·6 24·7 25·4 21·1 19·3 | 70·0 91·5 89·5 87·3 90·5 84·5 92·6 84·0 90·7 86·0 89·3 | 8·3700 14·1219 15·6136 16·7341 16·7668 17·1558 17·5028 17·5123 16·8418 14·6645 13·0468 | 29·874 29·923 29·892 29·831 | 57·0 59·5 63·3 64·5 65·7 68·5 69·5 71·7 71·0 | 55·7 57·2 59·7 61·3 60·4 58·6 59·2 61·8 60·5 | 1·3 2·3 3·6 3·2 5·3 9·9 10·3 9·9 10·5 | ·960 ·920 ·890 ·900 ·840 ·722 ·710 ·720 ·710 | 127·0 142·0 148·0 150·0 | Cloudless. Mountains clear. Wind N.N.E. Cool. Wind N.W. Wind S.W. Clouds about in patches.

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B.—JANUARY 1, 1851. Watch slow 3′ 45″ mean time.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. | Black Bulb |
7.34 to 7.41 a.m. 8.38 to 8.45 a.m. 9.44 to 9.51 a.m. 10.46 to 10.53 a.m. 11.50 to 11.57 a.m. 12.06 to 12.13 p.m. 12.58 to 1.02 p.m. 1.45 to 1.52 p.m. 3.15 to 3.22 p.m. 4.27 to 4.34 p.m. 4.36 to 4.43 p.m. 4.45 to 4.52 p.m. 4.56 to 5.09 p.m. 5.12 to 5.18 p.m. | 10·0 16·0 19·5 21·0 21·5 24·1 23·9 21·4 18·1 10·2 9·8 8·5 5·6 3·8 | 69·4 70·0 74·7 78·2 81·2 88·0 87·2 84·5 82·5 82·0 84·0 85·0 85·0 84·0 | 8·4200 13·3920 15·3660 15·8550 15·6950 16·4603 16·4432 15·0870 13·0320 7·3746 6·9482 5·9670 3·9312 2·6942 | 29·948 29·891 29·850 29·798 29·778 | 55·4 58·9 63·2 66·7 69·8 70·3 71·0 71·3 71·3 70·0 67·5 68·7 | 54·0 57·7 61·7 62·4 58·3 56·0 56·7 57·5 57·1 59·5 62·7 62·2 | 1·4 1·2 1·5 4·3 11·5 14·3 14·3 13·8 14·2 10·5 4·8 6·5 | ·953 ·970 ·960 ·870 ·688 ·625 ·625 ·633 ·625 ·708 ·855 ·810 | 104·5 115·0 120·0 117·0 122·5 117·0 | Mist rises and drifts westward till 7.30 a.m. Wind N.W., clouds rise. Sunset cloudless.

C.—JANUARY 2, 1851. Watch slow 3′ mean time.

Hour | Act. | Temp. Act. | Act. reduced | Barom. | Air | D.P. | Diff. | Sat. | Black Bulb |
10.02 to 10.09 10.20 to 10.24 12.03 to 12.10 p.m. 12.22 to 12.25 p.m. 2.04 to 2.08 p.m. 2.10 to 2.14 p.m. | 19·2 22·6 24·7 25·9 23·3 23·8 | 71·0 79·0 89·2 95·5 91·5 93·0 | 15·8592 16·9048 16·6972 18·6796 15·4479 15·6128 | 29·861 29·858 | 64·5 65·6 69·0 70·7 71·2 | 60·6 61·4 59·3 57·5 61·0 | 3·9 4·2 9·7 3·2 10·2 | ·878 ·872 ·728 ·650 ·718 | 116·0 119·0 112·0 | Low, dense fog at sunrise, clear at 9 a.m. Hills hazy and horizon grey.

Appendix A | Appendix B | Appendix C | Appendix D | Appendix E | Appendix F |
Appendix G | Appendix H | Appendix I | Appendix J | Appendix K | Appendix L |