14 W. H. WARREN. 
currents of the order .— 10—** amperes, and so push the examina- 
tion of sulphur much further than: would otherwise have been 
possible. It is believed that this investigation is the first thorough 
and precise examination that has ever been made on the electrical 
properties of a pure non-metallic substance. This work has been 
_written out, but is not yet published. 
Electro-magnetic Mechanisms.—A method has been devised of 
obtaining complete information as to the electric and magnetic 
behaviour of one type of such a mechanism during action. From 
the data obtained, Mr. Pollock has been able to deduce some 
‘interesting facts as to the efficiency and sources of loss in such 
mechanisms, in addition, to the work done last year. 
Magnetic Traction.—An investigation of the principles of 
magnetic traction has been just completed from what is believed. 
to be a novel point of view. The predictions of theory have been 
shown to agree (with one remarkable exception) with experiment, 
and a new method of calculating the forces between magnetic 
poles has been reduced to a form suitable for easy computations. 
Gravity Meter.—Mr. Pollock’s investigations of the secular 
variations and temperature corrections of the instrument have been 
sufficiently satisfactory to embolden Professor Threlfall to design, 
(with the assistance of Mr. Cook), a practical and portable form 
of instrument, which is in course of construction in the workshop 
as opportunity offers, and which is about half-way on the road to 
completion. The accuracy arrived at is about the same as that 
obtainable by good pendulum experiments. 
Professor Liversidge, during the year, has been occupied in 
arranging the chemistry and metallurgical work in connection 
with the new course in mining engineering. At the Hobart 
meeting of the Australasian Association for the Advancement of - 
Science, he read two papers, one ‘‘On the presence of Magnetite 
in certain minerals and rocks,” and another “On Iron rust 
possessing magnetic properties.” He also read a paper before 
this Society ‘‘On Native Weapons.” He is at present investi- 
