80 



THOUGHTS ON TnE INFLUENCE OF ETHER 







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If the form of the mass of heated ether be determined by the causes I have cited, it 



earth were at D, the parts would appear as described in figure 1. If the earth were at F (the position occupied 

 by our planet about the 5th of March), the sun's axis and the poles of the ecliptic would appear to coincide, but 

 the earth being at E, they deviate by N, which is the sine of an arc of 15° whose radius is 7°. 

 Let us ascertain the value of this deviation in degrees of the sun's surface. 



Radius : Sin. 15° : : Sin. 7° : Sin. 1° 48' 27". 

 We are now prepared to picture to ourselves the sun as it appeared to Sccchi on the 21st March, 1852. We 

 have ascertained that the apparent inclination of its axis to the poles of the ecliptic, was 1° 48' 27'', and we have 

 the data for determining the relations of all its parts to the great circles which arc the landmarks of astronomy. 

 In Fig. 3, the circle represents the sun's disc. The line A B is a circle of declination, D is the equinoctial 



line. E F is the ecliptic. G H, the poles of the ecliptic. 

 I K, the sun's axis. L S T M, its equator, and ORP, the 

 line of maximum heat, which Secchi observed on the 20th, 

 21st, and 22d March. 



My purpose is to ascertain the measure of an arc of the 

 sun's surface R S, embraced between the equator and the 

 line of maximum heat. 



On the 21st March, the angle A U G-, or that embraced 

 D between a circle of declination and the poles of the ecliptic, 

 is 23° 27' 30". 



Wo have ascertained that the angle Cr U I, or the appa- 

 rent deviation of the sun's axis from the poles of the ecliptic 

 on the day named, was 1° 48' 27". By adding these 

 together, we shall have 25° 15' 57", or the angle embraced 

 between the sun's axis and a circle of declination. 

 B Secchi informs us that when he made his observations, 



the sun's equator was 2.6' north of the centre of the disc. In Fig. 3, this is represented by U T. He found the 

 point of maximum heat to bo 3' north of the centre of the disc, U R in the figure. 



On the 21st March, the sun's semi-diameter is 16' 4.6". This is the radius of the arcs of which Secchi has 

 furnished us with the sines. 



In our investigation we require the measures of these arcs, and their difference in degrees of the sun's surface. 



Arc U T. 

 Sin. 16' 4.6" : Sin. 2' 36" : : Radius : Sin. 9° 7' 51". 



Arc U R. 

 Sin. 16' 4.6" : 3' : : Radius : Sin. 10° 45' 23". 

 10° 45' 23"— 9° 7' 51" — 1° 38' 32". 

 We have now ascertained the measure of the arc T R, which will enable us to attain our end ; the measure of 

 the arc S R embraced between the sun's equator and the line of maximum heat. 



T R is a part of A B, the circle of declination in which Secchi made his observations. We have ascertained 

 that it is inclined to the sun's axis 25° 15' 57". The angle which it forms with the solar equator is the comple- 

 ment of this, or 64° 44' 03". The last is the measure of the angle R T S. 



Arc S R. 

 Radius : Sin. 1° 38' 32" : : Sin. 64° 44' 03" : Sin. 1° 29' 06". 



