COLUMBIA, WASHINGTON TEEEITOEY, AND VANCOUVEE ISLAND. 
163 
part of a unit= 77*66 miles ; w, the angle which isodynamic lines make with the meridian 
measured from the north round by west, is 44° 6'. Column 11 of Table IV. contains 
the most probable value of the total force at each station, and the probable error of 
one such value is +0*044. 
Declination. 
Table V. is similar in character to Tables II. and IV. ; by it we find (x) the increase 
of declination for one mile of longitude = + 0'*230, and (y) the increase of declination for 
one mile of latitude = +0'*423 ; * the distance between lines of equal variation 1' apart 
=2*0756 miles; therefore, for 1° of difference in the declination, the distance is 124*54 
miles ; u , the angle which lines of equal declination make with the meridian measured 
from the north round by west, is 61° 27'. The most probable decimations are shown in 
column 5 of Table V., and the probable error of one such result is +27 / . 
The results contained in Tables II., IV. and V. are represented graphicaly in 
Plate III., which exhibits a map of the country surveyed, with the lines of equal incli- 
nation, declination, and intensity drawn upon it. 
Table I. — Dip. 
1. 
2. 
3. 
4. 
5. 
6. 
7. 
Date. 
Needle. 
Station. 
Poles direct. 
Poles 
reversed. 
Dip. 
Mean dip. 
1858. August 19 ... 
1 
Esquimalt 
71 18-94 
71 42-06 
71 30-5 
1 
1859. March 
18 ... 
4 
„ 
71 31-55 
71 42-78 
71 37-2 
L 71 34-2 
1860. March 
22 ... 
1 
„ 
71 23 00 
71 46-20 
71 34 9 
J 
1858. Oct. 
4 ... 
1 
Sumass Prairie 1 
72 12-08 
72 29 15 
72 20 6 
1 70 Q9.A 
5 ... 
4 
72 16-66 
72 29-88 
72 23-3 
J 
1859. Jan. 
31 ... 
4 
Nisqually 
70 29-62 
70 49-56 
70 40-0 
July 
4 ... 
1 
Schweltza Lake 
71 57-31 
72 13-68 
72 05-8 
l 79 03*Q 
5 ... 
1 
71 50-44 
72 13-25 
72 01-9 
Sept. 
7 ... 
1 
Chilukweyuk Lake 
72 19-60 
72 42-40 
72 310 
1860. May 
3 ... 
1 
Port Vancouver, W. T 
69 02-83 
69 31-88 
69 17-4 
21 ... 
1 
Dalles, W. T., 3-mile camp 
69 29-90 
69 53-80 
69 41-8 
June 
1 ... 
1 
„ 8-mile camp 
69 55-12 
70 13-66 
70 04-5 
July 
9 ... 
4 
On Ashtnolou River 
72 29 09 
72 44-79 
72 36-9 
August 18 ... 
1 
Ashtnolou Station 
72 16-80 
72 37-20 
72 27 0 
Nov. 
13 ... 
4 
Inshwointum 
72 34-75 
73 02-90 
72 48-8 
1861. March 26 ... 
4 
Fort Colville 
72 51-81 
73 33-93 
72 42-9 
April 
2 ... 
4 
„ 
72 44-60 
72 56-50 
72 50-6 
1 
12 ... 
4 
„ 
72 32-40 
72 44-70 
72 38-5 
23 ... 
4 
Chemikane River 
72 34-20 
72 36-70 
72 35-5 
iJ 
May 
19 ... 
1 
71 45-40 
72 24-60 
72 04-2 
31 ... 
4 
Sinyakwateen 
72 29-60 
72 42-00 
72 35-8 
1 79 Q+Q 
31 ... 
1 
72 17-31 
72 50-61 
72 34-0 
> ( O'* it 
June 
19 ... 
1 
Pack River 
72 31-62 
72 59-44 
72 45-5 
23 ... 
1 
Chelemta 
72 54-56 
73 21-50 
73 08-0 
July 
6 ... 
1 
South Crossing (Kootenay) 
72 37-50 
72 59-00 
72 48-1 
12 ... 
1 
On Kootenay River 
72 57-31 
73 17-06 
73 07-2 
August 19 ... 
1 
Tobacco Plains (Kootenay) 
73 16-06 
73 29-44 
73 22-9 
14 ... 
1 
Wigwam River Station 
73 27-06 
73 34-62 
73 31 0 
2 ... 
Akamina Station ... 
73 34-12 
73 51-31 
73 42-7 
MDCCCLXIV. 
