430 
The deviation of one of these persons was 
—1°.4. The settings of the other were 
always positive when made from the posi- 
tive side and negative when made from the 
negative side. The average deviation of 
a single setting made by this person was in 
absolute amount 1°.5. 
When settings are made by a person 
while standing squarely before the instru- 
ment with his head much inclined to one 
side, the deviations are always clockwise 
when the inclination is to the right, and 
counter-clockwise when the inclination is 
to the left. When the inclination is small it 
is, of course, not possible to predict the 
signs of the deviations. The settings of one 
observer, and of only one among several 
who were examined, were exceptions to the 
rule when the head was inclined as much 
as 20°. In Table VI. the first line gives 
the deviations of an observer fairly repre- 
sentative of the average, and the second 
line those of the exceptional person just 
mentioned. The inclinations were very 
nearly 20° in all cases. - 
SCIENCE. 
[N.S. Von. X. No. 248. 
THE DEVONIAN SYSTEM IN CANADA. 
II. 
2. ONTARIO AND KEEWATIN (HUDSON BAY).. 
While Logan was exploring the Gaspé: 
sandstones in 1843, Mr. A. Murray, then 
Assistant Geologist to the Canadian Sur- 
vey, was engaged in a ‘‘geological ex- 
amination of the district lying in a gen- 
eral line between Georgian Bay, on Lake 
Huron, and the lower extremity of Lake 
Erie.’’ In his report on that year’s opera- 
tions, published in 1845, Mr. Murray cor- 
rectly, and for the first time, regards the 
rocks at Port Colborne, Cayuga, ete., which 
he calls the Upper Limestones, as the equiy- 
alents of the Corniferous limestone of the 
State of New York. The black bitumi- 
nous shales at Kettle Point, Lake Huron and 
on the Sydenham River, that he examined 
in 1848, he at first thought to be part of the 
Hamilton formation, but in 1855 he re-ex- 
amined these shales and some of the expo- 
sures on the Sable River and in the town- 
ship of Bosanquet, in company with James 
TABLE VI. 
Horizontal settings made, when the head was inclined | Vertical settings made aeten the head was inclined 
to the Oo the 
Ob- Left, Right, Left, Right, 
server. = 5 5 : F 5 = ; 
using the|using the| using using using using using using using using using using 
left right both the left |the right} both | theleft |theright| both the left |the right} both 
eye. eye. eyes. eye. eye. eyes. eye. eye. eyes. eye. eye. eyes. 
1 —2°.3 | —0°.9 | —2°.0 | +2°.1 | +1°.4 | +1°.9 | —1°.9 | —2°.2 | —1°.9 | +0°.7 | +1°.5 +1°.4 
2 +1 .3 |+3 .4 | +2 .1)—0 .6|-+0 4H .4/+1 .1/+2 .2 | +1 .2/—0 .6|—1 .0| —2 .4 
When the observer lay on one side on a 
horizontal shelf, with the line joining his 
eyes vertical, and with head well screened 
for some time before he made his settings, 
the deviations were in all cases clockwise 
if he lay on his right side and counter- 
clockwise if he lay on his left side, whether 
he used one eye or both. The magnitudes 
of the deviations, though very different with 
different people, were often as great as 20°. 
B. O. PErRce. 
THE JEFFERSON PHYSICAL LABORATORY, 
- HARVARD UNIVERSITY. 
Hall, upon whose authority the former were 
decided to represent the lowest member of 
the Portage and Chemung group and the 
latter the Hamilton formation. But this. 
statement was not published until 1857. 
The discovery of the Oriskany sandstone 
at Cayuga would seem to have been made, 
or rather first recorded, by E. Billings, in 
May, 1860. For, in the preface to his now 
classical paper ‘On the Devonian Fossils of 
Canada West,’ Mr. Billings says that the 
‘* Devonian rocks of Canada West consist 
of portions of the Oriskany sandstone, 
scat 
