the highest part of the sled frame to aid in 

 keeping the sled upright. The camera was 

 positioned on the sled 1 m. above the runners, 

 and aimed forward 45° from vertical. The 

 large-capacity film magazine (250 frames) 

 and rapid recycling time (12 seconds) of the 

 capacitor for the light permitted up to 250 

 photographs to be taken at 15- second intervals 

 on one film load. The sled was towed at 

 1-1/2 to 2 knots for 15 to 60 minutes at each 

 station. Thus the linear distance along the sea 

 bottom between photographs was 12 to 17 m. 

 The 28-mm. lens gave a photograph of 1.2 

 square meters of bottom area in each frame. 



The numbers of photographs taken at stations 

 5, 42, 44, and 45, respectively, were 212, 70, 

 112, and 20 (total, 414). The film was black- 

 and-white panchromatic that has a speed 

 rating of ASA 125. 



A photographic print, 7-1/2 by 11-3/4 cm., 

 was made from each negative. Only a portion 

 of each print was used for counting and 

 measuring animals. A template was placed 

 over each print that blocked off all ex- 

 cept 0.46 square meter of foreground area. 

 Animals larger than 5 cm. were identified 

 and counted. Table 2 is a summation of the 

 c ount s . 



Figure 2. — Front-oblique view of sled-mounted photographic unit. Camera (A) is mounted above the electronic flash 



tube (B) in the circular portion of sled frame. 



