174 HOW TO STUDY BIRDS 



to carry six double plate-holders. The reflecting 

 camera is heavy and can most easily be carried in 

 hand by the handle on top. I have never used a 

 case for this, as it involves too much extra weight. 



If possible the plate-holders should fit both the 

 general and reflecting cameras interchangeably, for 

 it is a great advantage to be able to apply one's whole 

 stock of plates afield to either or both cameras at will. 

 Sometimes, especially on expeditions to strange and 

 distant places, I have fallen in with game which re- 

 quired the use of one or the other type of camera ex- 

 clusively, and many plates. To have the holders in- 

 terchangeable under these circumstances practically 

 doubles the stock. Most dealers sell a special holder 

 with their camera, probably through business neces- 

 sity, but some of these will fit others. 



The number of plates to be taken afield on a day's 

 jaunt will depend altogether upon probable need. 

 On a long walk when hunting for new material, es- 

 pecially when no subjects have been found In advance, 

 the dozen plates in the carrying-case of the camera 

 will usually suffice. In colonies of water-birds I 

 sometimes use sixty plates In a day, and thus have 

 thirty holders. The extra ones are carried In another 

 carrying-case, with the overflow from this in a creel, 

 wrapped In a dark cloth. 



The only plates which should be considered for this 

 work are those of the maximum rapidity. The Lu- 

 mlere Sigma plates are the fastest I know of at pres- 

 ent, and are splendid for extremely rapid exposures 



