210 



Brigade-Major Kater on the Light 



Cassegrainian Telescope. 

 Diameter of the circular 



opening in the paste- inch. 



board - - 3, 50 



Diameter of the back of 



the small mirror - 1,375 

 Length of the arm - 1,063 

 Thickness of the arm 0, 20 



Gregorian Telescope. 

 Diameter of the large mir- inch, 

 ror - ' 3, 95 



Diameter of the back of 



the small mirror - 0, 95 

 Length of the arm - 1, 50 

 Thickness of the arm 0,175 

 Length of a bar containing 



the adjustment - 0, 70 

 Its width - - 0, 15 



Diameter of three semi- 

 circles used as rests for 

 the great mirror - 0,375 

 From the above measures the following calculations were 

 made. 



Cassegrainian Telescope. 

 Area of the circular open- inch, 

 ing in the paste-board 9,621 

 Area of the back of the 

 small mirror to be de- 

 ducted - 1,485 

 Area of the arm to be de- 

 ducted - 0,213 



,1,698 



Area of the portion of the 

 mirror exposed to the 

 light 



7,923 



Gregorian Telescope. Inch. 



Area of the large mirror 12,254 

 Area of the back of the 

 small mirror to be de- 

 ducted - 0,709 



Area of the arm to be de- 

 ducted - 0,263 



Area of the bar contain- 

 ing the adjustment to 

 be deducted 0,105 



Area of the three semi- 

 circles to be deduct- 

 ed - - 0,166 



1,243 



Area of the portion of the 



mirror exposed to the 

 light - - 11,011 



