54 DEPARTMENT OF THE NATAL SERVICE 



6 GEORGE V, A. 1916 



in operation, as between finishing with one batch of larvae and starting a second batch, 

 the boxes are raised from the water, dried, and their inside given a fresh coating of 

 copper paint in order to prevent the parasites that may have infected one batch from 

 infecting the following one. 



PADDLES. 



The paddles are paired structures about 9 feet long. Ours were 8 inches broad at 

 one end and tapered gradually to 4 inches at the other. They were attached to 1 inch 

 gas piping by clips such as are commonly used by plumbers in fastening gas piping to 

 walls. The action of the paddles is such as to draw fresh salt-water in through the 

 windows on the bottom of the rearing box, give it a circular and upward movement in 

 the box, and pass it out through the side windows. This purpose is accomplished by 

 setting the front edge of each paddle slightly downward. In this way, not merely was 

 the water made to circulate, but its velocity could be adjusted, a most important thing 

 in the rearing of the fry, according to officials at Wickford. The velocities used at 

 Long Beach, estimated by the length of time it took a light cork to float in the water 

 around a circle of 15 feet circumference were 1 foot per second, down to 1 foot in 

 1§ seconds. The writer was unable to see any differences between the effects of these 

 two velocities on the larvae, the dominant factors being the low temperature of the 

 sea-water and the excessive development of plant parasites. 



THE POWER. 



Our motive power was a two-horse-power horizontal engine made by the Fair- 

 banks Morse Company. Though it was required to move the paddles in only four 

 boxes, the pond is so sheltered from winds in every direction that the engine could 

 easily generate sufficient power to run the machinery of a full Wickford plant of 

 twenty-four boxes. In fact, if it is found after next season that the pond is not suit- 

 able for a permanent rearing plant, the engine and gearing can be removed and the 

 equipment tried elsewhere. After the first week, during which the batteries and the 

 wiring gave us some trouble, the engine ran for nearly a month, day and night, with 

 only a few short stoppages for cleaning and adjustment. 



ROUTINE WORK. 



As soon as a sufficient number of larvae were placed in the four boxes, regular 

 routine work was established. The first step, of course, was to secure a sufficient 

 number of mother lobsters whose eggs were all hatching at the same time. Eight or 

 ten of these were placed in one of the boxes, and at the end of two days a sufficient 

 number of larvae had hatched out to stock another box. ' Two of the staff were detailed 

 to count out between 5,000 and 8,000 fry by means of a dip net. An automatic 

 counter held in one hand and operated by the thumb enabled each man to count out 

 the exact number of larvae which it was desired to transfer to each box. 



All the boxes having been stocked in this way, routine work consisted in arrang- 

 ing a division of the work among the staff. For most of the time there were only 

 three of us, and consequently each man was on duty for eight hours out of the twenty- 

 four. The longest watch was felt to be the one lasting from 11 p.m. until 7 a.m. the 

 next morning. During each watch the engine had to be supplied with gasolene, with 

 water for cooling the cylinder, and with plenty of oil for lubrication. In addition 

 to these duties, each man during his watch had to scramble eggs or macerate liver or 

 mackerel and feed the fry every two hours. The work was anything but a " summer 

 outing," though some of the local people evidently thought so at first. Possibly, 

 reader, you may think so, too. But if you had taken your turn at the work, night 

 and day, Saturdays and Sundays, week in and week out, for a month; and if in 

 addition you had attempted to carry on some systematic scientific research during 

 the day, your little delusion about our experiments being a summer outing would 

 soon have been dispelled. 



