52 NOVA SCOTIAN GEOLOGY—HONEYMAN. 
and again without the pilates, each measurement being preceded 
and succeeded by tests of the electrical similarity of electrodes 
and plates. Without the plates the current had to pass across 
two surfaces of contact between amalgamated zine and electro- 
lyte. With the plates it had to cross ten such surfaces. If there 
had been any transition resistance, therefore, the measured resist- 
ances in these two cases should have been different. In no ease, 
however, was I able to detect any difference greater than could 
be accounted for by the mere insertion of the- plates. In some 
experiments in which I used a connecting tube so small that the 
resistance of the cell was about 4,000 ohms, I could detect no 
difference at all. In others in which I used a tube of larger 
bore, so that the resistance was about 1700 ohms, differences 
were noticeable, but they were not such as to necessitate the 
assumption of a transition resistance to account for them. 
The apparatus which I used enabled me to measure resist- 
ances accurately to ‘1 ohm. It is therefore clear that the 
transition resistance which the current meets in passing eight 
times across the bounding surface between amalgamated zinc 
electrodes, of the area mentioned above, and solution of zine 
sulphate, does not amount to one-tenth of an ohm, and that 
therefore the transition resistance at one such surface is not so 
much as .0125 ohm. 
This result was sufficient for the purpose for which I 
made the experiments. 
The above experiments were made in the Physical Labora- 
tory of the University of Edinburgh. I am indebted to Prof. 
Tair for his kindness in furnishing me with the necessary 
apparatus. 
Art. VII. Nova Scotian GEOLOGY—HALIFAX AND COLCHESTER 
CountigEs. By Prof. D. HonrymMan, D.C.L., &c. 
(Read 14th May, 1883.) 
By looking at the Map of Nova Scotia it will be observed 
that the Counties of Halifax and Colchester are large. Halifax 
County extends from Lat. 62 deg. 13 min. to 64 deg. 5 min, The 
ong . 
