94 Generating Economic Cycles 



orbit), it is easy to calculate how much above or 

 below the level Ee'E'e the end of the pointer runs. 

 When in the direction SE or SE', of course the 

 Venus-carried pointer has its extremity on the Earth's 

 path; when in direction Sve or Sv'e', at right angles 

 to EE', the end of the pointer is at its farthest from 



Figure 25. The transit regions (pp' and qq') in the Earth's orbit. 



the plane Ee'E'e. The inclination of the orbit of 

 Venus being about 3° 23y, and the distance Se 

 (the Earth's distance from the Sun) being about 

 91,430,000 miles, ^ it is easily calculated that the 

 extremity of the pointer passes above e and below e' 

 at a distance of about 5,409,000 miles. At any other 

 point as P or P', the end is above or below by an 

 amount less than 5,409,000 miles in the same degree 

 that PM or P'M is less than eS, or e'S (PMP' being 

 drawn square to EE')-" 



1 Proctor's work, Transits of Venus, was published in 1875. Since 

 that date the mean distance of the Earth from the Sun has been as- 

 certained to be about 92,900,000 miles. The difference between Proc- 

 tor's figures and the real distance affects the accuracy of his subsequent 

 calculations. 



