8 British Association for the Advancement of Science. 



instantly set about drawing up their boats and placing their small 

 craft in more secure places ; early the next morning a violent storm 

 came on, which did much damage upon the coast, to those who 

 had not been similarly forewarned. It might perhaps be accounted 

 for by supposing that on these occasions the intervening air be- 

 came actually converted into a large magnifying lens. 



Magnetic Intensity. — Determinations of the value of the ter- 

 restrial intensity have been obtained at between forty and fifty 

 widely scattered stations, principally in the southern hemisphere, 

 where such determinations had been previously a great desider- 

 atum. 



The number of separate determinations collected in this Report 

 exceeds six hundred, and the number of stations falls a little short 

 of five hundred. They are the work of twenty-one observers, 

 and of these the observations of seven have been hitherto unpub- 

 lished. 



Beer. — Mr. Black communicated a paper ' On the Influence of 

 Electricity on the processes of Brewing.' According to his state- 

 ments, a thunder-storm not only checks the fermentation of worts, 

 but even raises the gravity of the saccharine fluid, and developes 

 in it an acid. This eflect is , witnessed principally when the fer- 

 menting tun is sunk in moist earth, and may be obviated by pla- 

 cing it upon baked wooden bearers, resting upon dry bricks or 

 wooden piers, so as to eflect its insulation. Mr. Black also stated, 

 that dming the prevalence of highly-electrified clouds, the fabri- 

 cation of cast iron does not succeed so well as in other states of 

 the atmosphere. 



Electrical Relations. — Dr. Faraday cautioned chemists against 

 considering electrical relations as affording, in every instance, con- 

 clusive proofs of what is a base and what is an acid. 



Electrical Protection. — A letter was next read, addressed by 

 Mr. Locke to Mr. W. W. Currie, of Liverpool, in which the latter 

 was requested to propose as a question, to the philosophers assem- 

 bled, whether, in the case of a monument one hundred and forty 

 feet in height, erectfed on the summit of a mountain fourteen hun- 

 dred feet high, augmented safety or danger would be the conse- 

 quence of attaching to it a conductor or paratonnerre. The col- 

 umn is sandstone, the mountain conglomerate, and in the vicinity 

 of the latter there is a mountain of still greater elevation. It was 

 resolved, that this letter should be, pro forma^ put into the hands 



