30 REPORT—1868. 
within a five-degree square, on each of two or three days of normal weather, would 
be a better guide to the seaman than a wind-rose purporting to show the proportion 
of different winds often from a small number of shsecmiiees made unconditionally 
in different years and seasons and in all kinds of weather. At all events, without 
undervaluing the method of averages and the importance of constants, it might, 
he believed, be said that it was to the system of comparing observations taken 
simultaneously over extensive portions of the earth’s surface that meteorology was 
likely to owe most progress for some time to come. Considering the interests at 
stake, the sooner, he thought, this system was generally adopted the better. Who 
could doubt that if we had had charts showing the directions and force of the 
wind, the isobars, &c. over the North Atlantic, the continent of Europe, and the 
British Islands, at a certain hour on each day, even for the last twelve months, we 
should be in a position to solve, wholly or partly, questions of great importance to 
science and navigation ? 
On Storm- Warnings in Mauritius. By Cuartes Metprum, M.A. 
By charting the winds and weather over the Indian Ocean for noon of each day 
during several years, and examining the connexions between the changes which 
took place at Mauritius and at various distances on all sides of it, the author ascer- 
tained that po heavy gale occurred within a distance of at least 1500 miles the 
existence of which was not indicated in the island by the barometer, winds, and 
weather. When signs of a hurricane at sea appeared at the Observatory notices 
were published in the daily newspapers, stating where the storm was raging, and in 
what direction it was travelling. The author explained in detail the grounds upon 
which these warnings were issued, showing that there were three classes of gales 
in the Indian Ocean south of the equator, and that each of them affected the wea- 
ther at Mauritius. As a general rule, the barometer never fell one-tenth of an 
inch below its mean height for the season except when a gale existed at a distance, 
and the character of the gale, and its bearing and course were determined by the 
direction and veering of the wind, the barometer, and state of the clouds and wea- 
ther. These results afforded the hope that similar rules might be successfully 
used on board ship in the Indian Ocean. In conclusion, the author expressed the 
opinion that the existence and course of storms in extra-tropical countries would 
yet be known at a distant station with far more certainty and precision than at 
present, for the winds in temperate climates, though more variable, were just as 
subject to law as those within the tropics. 
On some Meteorological Results obtained in the Observatory at Rome. 
By Pavre Seccet. 
The author began by stating the necessity that the climate of each observatory 
should be accurately known. He then expounded how he has calculated the tem- 
perature for every day of the year by simply taking the means for forty years of the 
same day of the year. The result was, that even after so long a term of observa- 
tions, no regular curve was obtained, not even if it was tried to smooth the irregu- 
larities by Mr. Bloxam’s method. The author, however, has not used this method 
except for five days, and only to ascertain that the irregularities did not disappear. 
The comparison of the normal curve obtained for Rome with those which are 
given for Paris, Berlin, Greenwich, Prague, Vienna, Bologna, show evidently that 
these irregularities are not due to chance, since they appear also in many other 
places, but that they are certainly an effect of the reaction of the sun’s heat on 
some particular places of the earth, combined with the law of the successive pro- 
pagation of storms. The law of this propagation has been studied, and it was 
found that the storms propagate from the British Islands to Italy in about two 
days; and the author pointed out the station of Nairn, in Scotland, as the best 
station which may indicate by telegraphic despatch the future state of weather in 
Rome. The author afterwards entered into a full explanation of the relation 
existing between the magnetical and meteorological perturbations, and he stated 
that in Rome these perturbations are signals of approaching storms. He at- 
tempted to explain them by the electrical currents which accompany the meteorolo- 
