+--------------+------+------+------+------+------+------+------+------+------+------+------+------+
| | Jan. | Feb. | Mar. | Apr. | May. | June | July | Aug. | Sep. | Oct. | Nov. | Dec. |
+--------------+------+------+------+------+------+------+------+------+------+------+------+------+
| Ediburgh | 1.8 | 1.4 | 1.4 | 3.8 | 12.3 | 20.8 | 28.2 | 19.1 | 7.0 | 2.3 | 1.1 | 0.8 |
| London | 0.6 | 0.5 | 1.6 | 6.6 | 12.7 | 18.3 | 25.5 | 19.2 | 9.3 | 3.1 | 1.7 | 0.9 |
| Paris | 0.2 | 0.4 | 2.3 | 7.5 | 14.9 | 21.6 | 22.0 | 17.0 | 9.9 | 3.5 | 0.4 | 0.4 |
| Netherlands | 2.2 | 1.8 | 3.7 | 6.5 | 14.0 | 14.7 | 15.6 | 14.7 | 10.3 | 10.1 | 3.8 | 2.5 |
| France | 2.2 | 2.8 | 4.1 | 8.4 | 13.8 | 18.7 | 14.6 | 13.5 | 10.0 | 6.3 | 3.1 | 2.4 |
| Switzerland | 0.2 | 0.3 | 0.5 | 4.9 | 11.9 | 22.9 | 29.9 | 18.0 | 9.8 | 1.1 | 0.3 | 0.2 |
| Hungary (a) | 0.0 | 0.1 | 1.6 | 5.7 | 20.9 | 25.0 | 23.2 | 15.9 | 5.7 | 1.3 | 0.4 | 0.2 |
| " (b) | 0.0 | 0.0 | 1.0 | 3.2 | 11.8 | 20.6 | 30.7 | 25.3 | 6.9 | 0.5 | 0.0 | 0.0 |
| United States| 0.1 | 0.1 | 1.2 | 4.0 | 14.3 | 25.0 | 27.2 | 20.4 | 5.8 | 1.4 | 0.3 | 0.1 |
| Hong-Kong | 0.0 | 2.1 | 4.3 | 8.5 | 12.8 | 23.4 | 14.9 | 21.3 | 10.6 | 2.1 | 0.0 | 0.0 |
| Trevandrum | 3.2 | 3.8 | 13.1 | 20.9 | 18.6 | 4.9 | 1.2 | 3.5 | 2.5 | 12.9 | 12.0 | 3.3 |
| Batavia | 10.4 | 9.2 | 11.1 | 10.5 | 7.9 | 5.5 | 4.3 | 3.8 | 5.4 | 8.8 | 12.2 | 10.9 |
+--------------+------+------+------+------+------+------+------+------+------+------+------+------+
31. Even at the same place thunderstorms vary greatly in intensity and
duration. Also the times of beginning and ending are difficult to
define exactly, so that several elements of uncertainty exist in data
as to the seasonal or diurnal variation. The monthly data in Table XI.
are percentages of the total for the year. In most cases the figures
are based on the number of days of thunder at a particular station, or
at the average station of a country; but the second set for Hungary
relates to the number of lightning strokes causing fire, and the
figures for the United States relate to deaths by lightning. The data
for Edinburgh, due to R.C. Mossman (64), refer to 130 years, 1771 to
1900. The data for London (1763-1896) are also due to Mossman (65);
for Paris (1873-1893) to Renou (66); for the Netherlands (1882-1900)
to A.J. Monne (69); for France(71) (1886-1899) to Frou and Hann; for
Switzerland to K. Hess (72); for Hungary (67) (1896-1903) to L. von
Szalay and others; for the United States (1890-1900) to A.J. Henry
(68); for Hong-Kong (73) (1894-1903) to W. Doberck. The Trevandrum
(74) data (1853-1864) were due originally to A. Broun; the Batavia
data (1867-1895) are from the Batavia _Observations_, vol. xviii.
Most stations in the northern hemisphere have a conspicuous maximum at
midsummer with little thunder in winter. Trevandrum (8 deg. 31' N.)
and Batavia (6 deg. 11' S.), especially the former, show a double
maximum and minimum.