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[[boxed]]
1862
June
19th
Thurs.
[[/boxed]]
had taken compass bearing of Sun marked [[strikethrough]] [[?]] [[/strikethrough]] spot in said Isd & having as I supposed determined the [[underlined]] true [[/underlined]] Azimuth of it by this in the usual way I deduced Variation. But I was certain there was an error some where for the Variation deduced only amounted to N. 52° W. something like 10° too small. The principle on wh. I have reduced the angle from Sun to observed object wh. I wished to determine its Azimuth has been to take the line extending [[strikethrough]] obliqrl[[guess]] [[/strikethrough]] obliquely from object to Sun as the hypotenuse of a triangle the Sun's Altitude for the perpendicular.
[[image - right triangle, the base labelled 'Result = 118'; the vertical labelled '30.73'; and the hypotenuse labelled '121.9'.]]
The mean of the 3 Sextant measurements of Sun to described spot in Island on the 16th Inst was 129°.9 : Altitude of Sun at the time 30°.73 Now by saying Az the hz. 121.9 2.08600 is to radius [[symbol]] 10.00000
So is perpendicular
30°.73 1.48756 As Radius 10.00000
___ Is to hoz. 2.08600
To Sine Angle 14° - 36' = 9.40156 So is sine angle 75° - 26 9.98574
________
2.07774
the result is = 118, this
added to Az. of sun (see Log June 16th end this Volume)N98-16-W
118
________
N 216 - 16 W
Bearing of Sun shot by compass 164°- 00
________
Variation N 52 - 16' W. Evidently to me erroneous. I try another way & it gives better - more satisfactory result
[[image - right triangle with base labelled '121.9', vertical labelled '30.23'; and hypotenuse labelled 'Result 125.7'.]]
As base 121.9 2.08600 | As Radius 10.00000
Is to Radius 10.00000 | Is to base 2.08600
So is perpen- | So is secant Angle 10.01338
________
dicular 30.78 1.48756 | To the Hy. 125.7 = ?.09938
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To Tangent Angle = 9.40156
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[[boxed]]
1862
June
19
Thurs.
[[/boxed]]
Now add the last result 125.7 = = = 125°- 42'
to the [[sun symbol]]'s Az N. 8°- 16 W
_______
Gives the true Az. of Sun marked spot N. 223° - 58' W
Bearing by Az. Com [[sun symbol]] Marked spot N 164°- 00 W
_______
Compass Variation = N 59°- 58' W
I was led to make a trial of Working out the matter as just recorded by an incident of this day. I taking Meridional obs I measured the distance of Sun to Budington Mt. wh. lies due E. of the vessel. I was not a little surprised to find that the angular distance was by then 90°. Now, Last winter when the sun was only just above the horizon, say 4° (Approximate) [[underlined]] at Meridian [[/underlined]], the distance from Sun to said Mt. just 90°.
True Altitude of Sun at this Lat. to-day 50°- 32' - 50" at Apparent Noon & distance from Sun to Bud. Mt. several degrees less than 90°. On ^[[occurring of]] this [[underlined]] new [[/underlined]] [[strikethrough]] [[?]] [[/strikethrough]] matter (to me new) I proposed the following experiment: I got [[strikethrough]] fluker [[/strikethrough]] Fluker to go aloft & suspend from the yard arm a line [[strikethrough]] ? [[/strikethrough]] reaching down near the ice, to wh. line was a ^[[pendant]] heavy weight. I took my position a little distance from said line on deck - my position such that the line [[strikethrough]] [[?]] [[strikethrough]] cut the center of Sun [[dtrikethrough]] It gave me [[/strikethrough]] a chosen shot on the land W. side of Rescue Bay. With my sextant I measured angular distance of Sun to Budington Mt. & then angular distance of spot directly under the Sun (the sighting line indicating at the spot) to Budington Mt. - the former measured 99° - the latter 106°! I expected a result [[underlined]] the proven[[guess]] from this. [[/underlined]] Again I tried it (short time after) the former (that is Sun to Bud. Mt) 102°; spot of land under sun to Bud. Mt. 111° Another trial, of like character of a different point on place from Bud Mt resulted thus: Sun to ^[[spot of land]] land 110°; sighted land under line to same land to wh. I take Sun 123°. Of course the experiment was a rude one but sufficiently effective in showing to me my misapprehension of the exact & proper way of Working
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