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might be considerable, the working expenses of such a system 
would be comparatively insignificant. Dr. Joule, in reply to 
a question which had been put the preceding meeting, stated 
that he estimated the total annual expense, including interest 
of capital, which would be incurred by removing the sewage 
of London to the fields, on his plan, at £1,140,000. The 
actual value of the manure being £1,440,000, a clear gain of 
£300,000. might be anticipated. On the other hand, the plan 
of the Board of Works would involve a dead loss of £230,000, 
and if the sewage were carried to the German Ocean the loss 
would be increased to, at least, £500,000. per annum. 
A Paper was read by Mr. Hopkins, entitled, “ On 
Weather, and the Operating Causes of its Changes.” 
In this Paper the writer does not furnish registered tables 
of the weather which is found in various places, as is often 
done by meteorologists, because he considers that an abundance 
of such documents are to be had in many publications; and 
so numerous and full are they as to give sufficient information 
respecting the mere facts, in the order in which they occur 
annually, daily, and hourly, to enable anyone, by careful 
analysis and comparison, to trace the forces or laws that 
pervade and govern the whole, and which give birth to the 
phenomena that accompany changes of the weather. But 
a knowledge of these laws is what is at present required. 
Having this object in view, the Author explains what he 
considers to be the main cause of the great disturbances of the 
atmosphere which occur, in varying forms, and to different 
extents, as shown in the numerous accounts which have been 
given of them over the whole surface of the globe. This 
cause is stated to be the metamorphoses of water produced 
by its union with, and sejiaration from, solar heat, which 
metamorphoses are shown to be almost constantly taking 
place over every part of that surface. But the operations are 
complicated, and so far concealed from ordinary observation 
