PROFESSOR MILLER, ON SPURIOUS RAINBOWS. 



28.5 



(F) 



Secondary bow. If m = 1.33453, r + S>-6f- 51°.17',5. If 

 v = 1.3348. tt+2>//-6^' = 51°.23',3. Diameter of the cylinder of water 

 = 0.0135 inch. 



According to theory, the distances of the brightest part of a prin- 

 cipal bow and of the 1st and 2nd dark rings from the geometrical bow, 

 are as 1.08; 2.48; 4.4. Whence, knowing the calculated radius of the 

 geometrical bow and the observed radius of the first dark ring, the 

 theoretical radii of the brightest part of the principal bow and that of 

 the second dark ring may be found. In the following comparison of 

 these with the mean of the results obtained by observation, it will be 

 seen that the differences between theory and observation are not greater 

 than might reasonably be expected. It will, however, be remarked that 

 in every instance the observed principal bow is a little nearer to the 

 geometrical bow than theory indicates. This, if not accidental, may be 

 due to an error in pointing, occasioned by the want of symmetry in 

 the distribution of the light in the principal bow. 

 Vol. VII. Part III. He 



