358 Proceedings of the British Association. 



The President then said, that as there were yet a great many 

 interesting communications to be brought forward, the Section 

 would reassemble at eight o'clock in the evening. 



THURSDAY EVENING. 



Mr G. W. Hall made a communication upon " The Connexion 

 observed at Bristol between the Weather and the Tide." He cora- 

 meuced by stating, that long and carefully-continued observation of 

 the weather at Bristol, together with a direct interest in becoming 

 possessed of rules for anticipating its changes, led to the following 

 theory, which was strikingly correspondent with facts : — 1st, That 

 the barometer very generally, indeed, almost invariably, undulates 

 at times corresponding with the changes of the moon, and at these 

 times it more frequently falls than rises. 2dly, That the weather 

 is ordinarily unsettled at these periods, continuing so for about two 

 or three days ; and for the most part the wind becomes high at 

 these times. 3dly, That as the weather settles (if it become at all 

 settled, since it not unfrequently remains in an unsettled state), so 

 will it continue until the next change of moon, or rather until the 

 recurrence of its disturbing influences. 4thly, That these variations 

 occur as regularly at the quarters of the moon as at the new and 

 full, and are then as fully marked. 5thly, That the period, about 

 five days, which determines the state of the weather, is derived 

 from the spring and neap tides, or the full influence of the sun and 

 moon upon them. — The only origin of these rules, he stated, was 

 actual observation. Very striking changes of temperature and 

 weather from intense frost to spring mildness, and then frost re- 

 curring, first led to marking this correspondence ; and so closely 

 has it been observed, and so fully established, that operations upon 

 a large scale, which are dependent upon the weather, have been 

 frequently and successfully conducted in accordance with these 

 rules. He considered the severe frost of 1813-14, which continued 

 about twelve weeks, with partial thaws intervening, and the severe 

 weather of succeeding winters, with their intermissions, to be 

 closely connected with the above rules. The partial rains also of 

 very dry summers have been found to take place at the same sea- 

 sons of change, insomuch that for amusement he had frequently 

 traced back the periods connected with the age of the moon, from 

 the thaws that took place in severe weather, or the rains occurring 

 in long-continued drought. Residing on the banks of the river, 

 and taking much interest in the operations of Professor Whewell 



