242 Prof. Ritchie on Magnetic Attraction. 
diaphragm d into c, and passes out through the pipes p p; this 
is now lighted, and it burns with a red unsteady flame; then 
the oxygen stopcock is turned gradually, when this gas passes 
through the holes into c, where it mixes with the hydrogen, 
and they come out in perfect union at the pipes p,p. The 
hydrogen cock is now fully opened, and the other cock gra- 
dually opened and adjusted till the lime-ball gives out its most 
brilliant light, when the hydrogen flame entirely disappears. 
The difficulties we encountered and the extraordinary shifts 
we were put to would be very amusing to you, but they are 
too long for a letter; suffice it to say, that in the end the ex- 
periment succeeded beyond our most sanguine expectation. 
The Pasha was delighted with its performance, and has taken 
the apparatus to his palace. I have since exhibited to him 
coal-gas light, which I managed much easier, and have drawn 
out my estimates for this light and oil; but no doubt the latter 
will be preferred, and I soon expect to be at work in putting 
in proper repair the lighthouses of Fanaraki. I am anxi- 
ously waiting your further description of Beale’s light, which 
I will also show to the Pasha, who takes great interest in all 
these matters. Witt Baweae 
XLVII. Additional Remarks on the Law of Magnetic At- 
tractions and Repulsions. By the Rev. Wit11aM RitcuHie, 
LL.D. F.RS.* 
S Mr. Fox still seems to think that the law of magnetic 
attractions is inversely as the distance between the ends 
of the attracting magnets, without any reference whatever to 
their form, the following considerations will, I think, convince 
him and every impartial inquirer that the supposed law has 
no existence in nature. 
Let two magnets be formed, of plate steel, into the annexed 
figure, having the poles at P, P’, and consequently further 
from the ends a, 6 than if the 
bar were rectangular; then the _ } 
attraction between those mag- 
nets will follow very different P Pp’ 
Jaw from that which exists when 
the bars are equally broad. The fact is, the supposed law 
obtained by measuring from the ends of the magnet will change 
with the length of the magnets, their form, and even with the 
uniformity of the temper. 
* Communicated by tke Author. 
