BULLETIN OF THE UNITED STA.TES FISH COMMISSION. 415 



201.— TREATMENT OF THE €ASEl,I>A.raffILiL,EK THERIMOITIETER. 



By LOUIS P. CASELLA. 



[From a letter to Prof. S. F. Baird.] 



1 regret to learn the difficulties you describe iu connection with some 

 of ray thermometers. I incline to believe that I could correct most of 

 the thermometers you may have which are not broken, and will be most 

 glad to do all in my power, if you will let me have them, telling your 

 assistant to pack them carefully so as to prevent their being further 

 disaiTauged. 



The usual precaution against disarrangement in the first instance is 

 that they should not be kept lying flat; that when sent from place to 

 place the indices should be lifted well up from the mercury. If by 

 chance a small portion of mercury gets over the bottom of the index, 

 hold it flat and use the magnet to draw it slowly up. With the head 

 quite raised, tap it smartly on the i^alm of the hand, the portions of 

 mercury become detached and fall down to the main column. Warm 

 tlie surface freely before the fire, then hang up ; they thus become 

 united. 



As these are the only thermometers that register the maximum and 

 minimum temperature they were adopted w'th my arrangement, and 

 have thus shown the temperature of all depths of the sea in a way that 

 has not yet been contradicted, though I regret this tendency to disar- 

 rangement which I have acknowledged from the first. Should you send 

 yours for repair, I propose adopting an arrangement of case that will, I 

 hope, enable mo to employ an easier kind of index. This I will try to 

 have ready so as to apply to yours or to part of them when they come. 



147 HoLBORN, London, E. C, May 21, 1884. 



203.-HATCHIi\G RfiACKFI^U AND 8PAIVI.«$II MACKEREL. 



By R. E. EAKLE. 



[From letters to Prof. S. F. Baird.] 



This morning, while at the fish-wharves, I discovered that nearly all of 

 the blackfish {Centropristis atrarius) were thoroughly ripe, and eggs 

 would run from fully 50 per cent, of the females in handling. I took a 

 number of thousand and impregnated them. They sink readily in salt 

 water, and have a diameter of i>V of an inch. I saved some iu alcohol 

 and glycerine. Many of the other species are well advanced and will 

 spawn in iwo or three weeks at most. I shall try to get a full series of 

 ovaries in alcohol for future examination. 



Charleston, S. C, March 25, 188Q, 



