7. Table of Specific Gravity of Bodies at 32° F. except water, which is taken at 39°·4.
| Water | 1·000 | |||
| Alcohol, pure | 0·791 | |||
| "proof | 0·916 | |||
| Mercury | 13·596 | |||
| Glass | 3 | to | 2·7 | |
| Brass | 7·8 | to | 8·54 | |
| Platinum | 21 | to | 22·00 | |
Weight of a cubic foot of water, at the temperature of comparison, 62·425 lbs. avoirdupois.
The pound avoirdupois contains 7,000 grains.
Air is 813·67 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 circumstances 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 to 1861. Months. | Mean Height of Barometer, reduced to 32° F., at the mean sea-level. | Mean Monthly Range of Barometer. | Mean of all the Highest Temp’s. | Mean of all the Lowest Temp’s. | Mean Temp. | Mean Temp. of Dew-point. | Mean Degree of Humidity. | Mean Number of Rainy Days. | Average Rainfall. | Average Amount of Cloud (10= overcast). | Prevalent Winds. | Sun above the Horizon on Middle Day. | Remarks. |
| Inches. | Inches. | ° | ° | ° | ° | Inches. | Hours. | ||||||
| Jan. | 29·932 | 1·44 | 43·2 | 33·7 | 38·3 | 35·4 | 89 | 11 | 1·8 | 7·7 | W. to N. | 8½ | The majority of the nights are frosty. |
| Feb. | 29·962 | 1·22 | 44·7 | 33·2 | 38·4 | 34·4 | 85 | 10 | 1·6 | 7·4 | S. to W. | 10 | 10 frosty nights on the average. |
| Mar. | 29·967 | 1·23 | 50·0 | 35·3 | 41·7 | 36·4 | 82 | 10 | 1·5 | 6·6 | N. to E. | 12 | 12 frosty nights on the average. Strong winds. |
| Apr. | 29·907 | 1·06 | 56·8 | 38·6 | 46·3 | 39·9 | 79 | 11 | 1·8 | 6·1 | N. to E. | 14 | 6 frosty nights on the average. |
| May | 29·931 | 1·02 | 64·4 | 44·2 | 52·8 | 45·5 | 76 | 11 | 2·1 | 6·1 | S. to W. | 15½ | Very rarely frost. |
| June | 29·960 | 0·89 | 71·2 | 50·2 | 59·2 | 50·8 | 74 | 11 | 1·9 | 6·1 | W. to N. | 16½ | Sun attains greatest North Declination, 21st. |
| July | 29·970 | 0·79 | 73·8 | 53·2 | 61·9 | 53·9 | 76 | 11 | 2·7 | 6·9 | W. to N. | 16 | |
| Aug. | 29·954 | 0·97 | 72·8 | 53·4 | 61·3 | 54·1 | 77 | 11 | 2·4 | 6·5 | W. to N. | 14½ | |
| Sept. | 29·997 | 0·95 | 67·4 | 48·9 | 56·9 | 51·1 | 81 | 12 | 2·4 | 5·9 | S. to W. | 12½ | |
| Oct. | 29·860 | 1·33 | 58·3 | 43·7 | 50·2 | 46·0 | 87 | 13 | 2·8 | 6·9 | S. to W. | 10½ | A few frosty nights. Heavy gales. |
| Nov. | 29·929 | 1·53 | 49·3 | 37·7 | 43·4 | 40·1 | 89 | 12 | 2·4 | 7·2 | S.W. | 9 | 11 nights frosty. |
| Dec. | 29·979 | 1·52 | 45·0 | 35·5 | 40·1 | 36·9 | 89 | 12 | 1·9 | 7·4 | W. | 8 | Sun attains greatest South Declination, 21st. |
| Year | 29·946 | 1·16 | 58·0 | 42·3 | 49·2 | 43·7 | 82 | 133 | 25·3 | 6·7 | ... | ... | |
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 |