674 
biological sciences) ; and our account covers 
only the more interesting or important papers 
in these two sections. A full list will be found 
in our Notes. 
In the physical section, Mr. F. N. Gisborne, 
the superintendent of the government telegraph- 
service, described a new system, devised by 
himself, to obviate the evil effects of electrical 
induction in underground and aerial conduct- 
ors. A number of diagrams were presented, 
illustrating the conditions obtaining in neigh- 
boring circuits ; and two or more circuits ar- 
ranged in the ordinary way, and the same 
arranged according to his method, were com- 
pared. The advantages of the latter arrange- 
ment were clearly set forth; and proofs of its 
efficiency were presented in a tabular statement 
of experiments made with a section of cable 
about three thousand feet in length, constructed 
under his direction, and laid underground be- 
tween two of the departmental buildings in 
Ottawa. The cable contains twenty indiffer- 
ently insulated conductors or wires, which are 
divided into pairs, two conductors being twisted 
together in each case. Each pair constitutes a 
metallic circuit, one conductor being used as 
a ‘return,’ instead of the earth-plates usually 
employed. The peculiarity of the invention 
consists in the twisting of these metallic cir- 
cuit conductors, as both wires are thus made 
to occupy an equidistant relationship with 
respect to any other conductor or pair of con- 
ductors in their vicinity. It was explained, 
that, by this device, a current introduced into a 
circuit is conducted down one wire, and up the 
other; and, the position of both wires being 
the same with respect to neighboring circuits, 
the inductive effect of the current passing 
down one wire is neutralized by the inductive 
effect of the same current passing up the 
return-wire. 
It was also theoretically demonstrated that 
the twisting of the wires of the metallic cir- 
cuits lessens the effect of induction of the 
current upon itself. When the wires of a me- 
tallic circuit are laid parallel throughout, the 
current induced from one wire into the other 
is in the same direction as the current itself 
passing in that wire; the effect of the current 
is‘ therefore prolonged, and retardation expe- 
rienced in a marked degree: whereas, when 
the wires are twisted closely (say, two turns to 
the inch), the wires occupy throughout their 
length a position approaching right angles with 
respect to each other; and the induced cur- 
rents are thereby materially lessened, and re- 
tardation rendered less appreciable. 
In the discussion which followed the reading 
SCIENCE. 
a ee ae ae 7 - 
of the paper, it transpired, that if a conductor 
were enclosed and insulated within another 
conductor (such, for instance, as a gutta-percha 
covered wire drawn through a metal tube), 
and both conductors were connected at either 
end with earth-plates, or other conductors, so 
as to form two independent closed circuits, the 
enclosed conductor might be employed to con- 
vey electrical currents, without any inductive 
effect being perceived, in a circuit extending 
parallel with, or in the neighborhood of, the 
outside conductor. The explanation of this 
condition is, that the outside conductor, which 
in this case cannot be used as a medium for 
communication, intercepts the induced currents 
on all sides of the inducing circuit, and in its 
closed cireuit absorbs them. 
As in such a system the outside conductors 
could not be utilized in the formation of circuits 
for purposes of communication, it is admitted, 
that, apart from the bulkiness necessarily at- 
tending it, the first cost of construction upon 
that plan renders the system comparatively 
impractical; whereas, in the system advanced 
by Mr. Gisborne, the construction is much 
cheaper, and all the conductors form an in- 
tegral part of the communicating circuits, so 
that space is economized to the fullest extent. 
A good deal of interest is being manifested 
in this invention which Mr. Gisborne has just 
now brought forward, although it has been a 
subject of investigation with him for some 
years past, the cable referred to in the paper 
having been ordered by the Dominion govern- 
ment during the summer of 1882. 
Mr. R. Steckel presented a paper on the form 
of the contracted liquid vein, affecting the pres- 
ent theory of the science of hydraulics, in 
which the author claims to propound a new 
theory of the efflux of liquids, and describes 
experiments by which he has sought to test it. 
Dr. T. Sterry Hunt, in his paper on the 
origin of crystalline rocks, maintained, in op- 
position to the plutonic and metamorphic hy- 
potheses of the origin of these rocks, a new 
one, designated the crenitic hypothesis (Greek, 
Kpyvy, ‘& Spring’), according to which they 
were formed, at an early period of the earth’s 
history, by the agency of circulating subter- 
ranean waters rising to the earth’s surface as 
springs. He supposes the previous existence 
of a chaotic layer, the last-congealed portion 
of a globe consolidating from the centre ; which 
layer, rendered porous, and permeated by 
waters, gave up to them the materials of quartz — 
and the felspars, after the manner of zeolites, — 
to be deposited at the surface. 
The action of © 
non-aluminous silicates, allied to pectolite or the — 
[Vou. III, No. 70 
; 
4 
