78 
Dr. Joule, F.RS., referring to recent magnetic disturb- 
ances, described the means lie made use of for determining 
the absolute horizontal intensity. A current of electricity 
was transmitted successively through a single-coil galva- 
nometer and his current meter, an instrument already 
described, consisting of a suspended flat coil of wire between 
two equal fixed coils. If the coils are infinitely close to 
one another, the current is given by the formula 
h being the radius of a circle of equal area to one of the 
coils, l the length of wire in one of the coils, and w the 
weight required to balance the suspended coil. The current 
in the galvanometer is determined by the horizontal inten- 
sity and the tangent of deflection. Therefore, by combining 
the two instruments, we obtain the horizontal intensity, 
which is equal to the square root of the force of attraction 
in the current meter, divided by the tangent of deflection in 
the galvanometer, multiplied by a constant. 
“On the Examination of Water for Organic Matter,” 
Part II., by Dr. R Angus Smith, F.RS. 
At present the conclusion only is given, as no abstract 
was prepared. 
The following may be considered as a summary of the 
results required for sanitary purposes. 
1. Quality of the organic matter, i.e. what is produced by 
standing under favourable circumstances for developing 
vegetable or other life ? 
2 and 3. Condition of the organic matter. Products of 
decomposition. Easily decomposed organic matter. These 
two can be estimated for sanitary purposes sufficiently by 
permanganate of potash. 
4. Nitrates as remnants of organic matter. 
5. Nitrites as remnants of organic matter. 
