107 
Mr. Wilde has also received a letter on the subject of his 
recent experiments in magnetism from Mr. Moses G. Farmer, 
of Salem, Mass., United States, dated November 9th, 1866, 
in which he says that he had obtained an increase of 31 per 
cent, in the power of a magneto-electric machine, by trans- 
mitting the current from the armature through coils of wire 
surrounding pieces of soft iron forming the prolonged ex- 
tremities of the permanent magnets of the machine. Mr. 
Farmer, in the same letter, adds ' “ I have built a small 
machine in which a current from the thermo battery excites 
the electro-magnet of your machine to start it, and after the 
machine is in action, a branch from the current of the 
magneto passes through its own electro-magnet, and this 
supplies the magnetism required. It is not exactly like a 
person standing in a basket and trying to lift himself — - 
because the electricity proceeds from the conversion of the 
mechanical energy, which must be continually supplied. 
Neither can it in any wise be likened to the various schemes 
for producing perpetual motion ; but depends on the prin- 
ciple, that the actual energy of the mechanical force, con- 
jointly with the potential energy of the magnet, can develope 
a greater amount of potential energy than is originally 
resident in the magnet, or, in other words, it is a method of 
converting part of the actual energy of the prime mover 
into the potential energy of magnetism.” 
Mr. W. L. Dickinson, having discovered an error in his 
calculation of the Occultation of Aldebaran (see Proceedings, 
December 11th, 1866, page 47), communicated the following 
results of the corrected computation. 
Calculation for the Observatory of Robert Worthington, 
Esq., F.R.A.S., Crumpsall, near Manchester, Lat. 53° 30' 5O0" 
N., Long. 0 h 8 m 5 6*1 6 s W. 
The Occultation of Aldebaran by the Moon, January 16, 
1867: — 
