24 
“The Microscopical Structure of Coal Plants ”’”— 
By Mr. W. W. MIDGLEY, F.R. Met.S. 
Read before the Geological Section. 


By an admirable series of lantern views Mr. Midgley illustrated and 
explained the cellular structure of Coal Plants. This was demonstrated by 
photomicrographic as well as nature-printed—that is printed by contact with 
the microscopic section—transparencies. The types of plants dealt with 
were—Lepidodendrons, Sigillarias (with the roots Stigmaria), Lyginoden- 
drons, Calamites, Sphenophyllites, and Ferns. The arrangement of the 
different parts of the vascular cryptogams, in transverse, tangential, and 
longitudinal section, were shewn, as well as the fruits, and the details of 
structure and their affinities with recent plants pointed out. 


“ Wehnelt Electrolytic Break ’—By Rev. A. H. FISH, B.A., B.Sc. 
At a Meeting of the Society on April 6th, 1899, the Rev. A. H. FisH 
exhibited and explained the new Wehnelt Electrolytic Break, applied to 
Induction Coils and X-ray Photography. ¢ 
The break was worked from the 210 volt Town Supply in connection 
with a six-inch and ten-inch Induction Coil. 
The Lecturer drew attention to the peculiar nature of the discharge, and 
to the transformation of, or superposition upon, the direct current of an 
alternate current of higher voltage due to the break. 
An opportunity was also afforded of comparing the results produced by 
an ordinary mechanical Contact-breaker, a Motor-driven Mercury-break, and 
the Wehnelt Break, when used in connection with an X-ray Tube and 
Fluorescent Screen, _ 

“Wireless Telegraphy”—By Mr. T. HETHERINGTON. 

Read before the Natural Philosophy Section. 
The Paper was a review of the magnetic induction methods of wireless 
telegraphy introduced by Mr. W. H. Preece, Mr. Sidney Evershed, and 
Dr. Oliver Lodge, and the Hertzian Wave Method of Signor Marconi. 
Magnetic induction between wires followed well-known laws. Mr. Preece 
arranged his circuits after the manner of ordinary telegraph lines with an 
earth return, while Mr. Evershed used horizontal coils and rectangles of 
large area. The latter’s experiments revealed a new phenomenon in the 
absorption by sea-water, which militated against the use of the method for 
lightship purposes for which it was designed. The application of the 
principle of syntony by Dr. Lodge was the most interesting recent advance. 
His (Dr. Lodge’s) experimental demonstration, in 1881, that the discharge 
of a circuit possessing inductance and capacity—and consequently a natural 
period of oscillation—induced sympathetic resonance in a similar circuit, 
suggested the use of tuned circuits, In practice horizontal coils were used, 
and the period of vibration was regulated by the use of condensers in circuit. 
With syntonic circuits it was possible to span distances otherwise com- 
mercially impracticable; and intervening obstacles—such as the buildings of 
