378 



C. C. Hutchins — Irregular Reflection. 



with the burning metal, we find that its reflection is very 

 closely represented . by Lambert's equation, departing slightly 



in the direction predicted by Searle for a furrowed cylinder. 



The preceding table gives the observations upon the sphere 

 of magnesia, a sphere prepared by painting an ivory ball with 

 carbonate of lead, a sphere of reddish colored clay, and finally 

 Very's results from his well known study of distribution of 

 lunar heat with respect to phase. 



In fig. 5 the observations for the red clay sphere are repre- 

 sented by the dotted line, and Very's observations by the line 



marked with crosses. Both depart widely from the theoretical 

 curve. It will be seen that for small phase angles the reflec- 

 tions are too large for all bodies investigated, and although 

 Very's observations extend only to 80°, yet judging from the 

 direction of the curve at that point, the same would be found 

 true for the moon. This may be due wholly or in part to 

 specular reflection, for in the case of the sphere the smaller 

 the phase angle the more would the specular reflection become 

 manifest. 



The result of these observations is to add emphasis to what 

 was said above of the flat surface ; that is, the manner of 

 reflection of a body is largely determined by the character of 

 its surface and is only to be determined by the study of that 

 body individually. 



Considerable interest attaches to the question whether the 

 reflecting power or albedo of a body is the same when meas- 

 ured by the photometric method as when the total reflected 

 energy is taken into account. The method of observation 

 above described permits of the estimation of the albedo for 



