52 REPORT — 1861. 



obtained in the above discussions are very small, the greatest being less than -77*^^ 

 of one scale division of the Roman bifilar ; in a discussion of a sufficiently large 

 series they would probably entirely vanish. Should, however, further proof be re- 

 quired that the local meteorological phenomena are unconnected with the varia- 

 tions of horizontal intensity, it will be found in plate 28 of the paper previously 

 cited on the horizontal intensity of the earth's magnetism, where it will be seen 

 that the simidtaneous variations of daily mean horizontal force from hour to hour 

 at six places (Makerstoim in Scotland, the Cape of Good Hope, Trevandnim, South 

 India, Singapore, Hobarton, Van Diemen Island, and Toronto in Canada) resemble 

 each other, excepting in minute points and in cases of marked disturbance. 



I should not tenninate the examination of this question without noticing that 

 Father Secchi has concluded that magnetic disturbances are predictors of change 

 of weather at Rome ; he has indeed given mmibers which seem to show that there are 

 most disturbances when the wind blows from the south at Rome. When it is re- 

 membered that magnetic distm-bances are experienced simultaneously on all parts 

 of the earth's surface, any connexion between them and the weather at Rome must 

 appear extraordinary. For the strict examination, however, of this question, there 

 are, however, several points to be taken into consideration, some of which it seems 

 to me have been omitted by Father Secchi. First, we should decide on the defi- 

 nition of a day of distm'bance ; second, we should determine how many of these 

 days occm- in a fixed number (say a hundi-ed) during which each wiud blew ; third, 

 it should be remembered that the gi-eatest mean magnetic disturbance occurs near 

 the epochs of the equinoxes, and that the amount for perihelion is greater than for 

 aphelion. As for these periods of the year, each place has a prevailing wind ; the 

 discussion for each place would give the greatest number of disturbances for these 

 winds: thus at Makerstoun the prevailing winds were south-westerly, and the 

 greatest number of distmrbances occun-ed in 1844 with south and west winds ; at 

 Rome the prevailing wind at these epochs is perhaps southerly, and at Singapore it 

 is probably westerly. 



As I am unacquainted with the observations made in the observatory of the 

 Roman College, I shall not venture to offer any suggestion as to the remarkable 

 results which have been deduced fr-om them. 



On the Law of Universal Storms. By William Danson, of Liverpool. 

 In the course of his paper the author insisted on the soundness of the general 

 views now prevalent regarding the theory of storms, and the regularity of their occur- 

 rence. He endeavoured to show that it was something like infatuation on the 

 part of seafaring men ignoring these laws — captains and commanders, as well as 

 ordinary seamen, included. It was a point of the greatest importance, at the pre- 

 sent time, to consider whether it was not desirable to adopt improved means to 

 secure the safety of traffic, leaving the rapidity of ships' passages as a secondary con- 

 sideration; and supposing this view of the subject to be recognized, it was worthy 

 of being taken into account whether the theory of what was now nautically known 

 as the " great circle sailing " was not the best to be adopted by our mercantile ma- 

 rine captains generally. He knew that, in insisting upon the practical utility of 

 recognizing this theory, he was in antagonism with the views of many experienced 

 seamen, whose opinions were entitled to profound respect; but he nevertheless 

 ventured to suggest, as worthy of the notice of the nautical public generally, that, 

 in a great number of eases, ships whose captains had followed the " gi-eat circle 

 sailing " theory had arrived safely at their respective destinations ; whilst other 

 vessels, imder the same thenuometrical and barometrical circumstances, but whose 

 conmianders had adhered to the hitherto received ideas of practical nautical navi- 

 gation, had met with a fate which it would only be painfid to dilate upon. Re- 

 ferring to the length and duration of storms, he said that the residts of several of 

 the most complete calculations indicated that, in the instances of stoniis, several of 

 them had extended as far as 3600 miles, and travelled at the rate of 50 miles an 

 hour, and that this is a moderate calcidarion. 



