|9J»] U. S FISH COMMISSION STEAMER ALBATROSS. 101 



and Fig. a cross-section. The messenger is made of cast iroii in two 

 parts, which are held in position ou the rope by lashings passed iu the 

 scores prepared tor the purpose. The key is shown in Fig. 10. 



WORKING THE APPARATUS. 



* " It is necessary first to regulate the buffer to cushion the stoppage 

 of the falling weights, which are, cylinder and frame, 38 pounds, clamp 

 4 pounds, messenger 8 pounds, total 50 pounds. The Blake adopted a 

 resistance of about 80 pounds (this resistance being of course constant 

 during the whole movement of the buffer), it having been found that 

 a blow ol that force resulted in no injury to the apparatus. 



"On the ascent the buffer must withstand not only the weight of the 

 50 pounds of metal, but also the resistance which the water offers to 

 the passage through it of the several parts of the apparatus. Moreover, 

 when the cyliuder emerges from the water it is full of that liquid and 

 with this increased weight would overcome the stated resistance of the 

 buffer and force the latter downwards until the lead was reached. To 

 meet these conditions it was not thought advisable to increase the re- 

 sistance of the buffer, which would involve a heavier blow against the 

 apparatus, but a rope-yarn seizing or stop was placed on the rope about 

 15 or 20 feet below the buffer, beyond which the latter could not pass. 



" Having secured the buffer to the rope about 5 or 6 fathoms above 

 the lead (a very heavy lead to keep the rope straight) and paid out 

 the length of rope required to span the stratum to be explored by the 

 cyliuder, the clamp and cylinder are attached, the latter being stis- 

 pended from the former as follows : 



"The rope having been placed between the two sliding chocks of the 

 clamp, the arm of the eccentric tumbler is thrown up, which moves the 

 chock M inwards ; then, by means of the adjusting screw, the chock L 

 is pressed against the rope, securing the clamp in position. The cylin- 

 der hangs 4 or 5 inches below the clamp and is supported by a loop of 

 soft wire which rests on the lip of the tumbler ; the ends of the wire, 

 being run through holes in the upper part of the frame of the cylinder, 

 are fastened permanently to the outer arms of the lever D, to which 

 the valve is screwed. It is seen that by this method of suspension the 

 weight of the cylinder and its frame is used to keep the valve closed 

 while paying out. The cylinder should be filled with water, poured 

 down through the upper sieve, to maintain the valve on its seat while 

 the cylinder is being immersed. Eope is then paid out slowly until 

 the cylinder is at the desired depth, when the rope is stoppered and 

 the messenger sent down. The messenger strikes the arm of the ec- 

 centric tumbler, throwing it down and tripping the cylinder. The 

 tumbler in falling relieves the pressure on the sliding chock M, which 

 is then free to recede from the rope. 



"Messenger, clamp, and cylinder fall together, the valve being held 



* Sigsbee. 



