212 



SCIENCE-GOSSIP. 



[Sept. 1, 18G5. 



Tresh-watek Aquaria. — In reply to E. C. the 

 bottom of the aquarium should have first from twenty 

 to fifty small pieces of charcoal strewed over it ; 

 upon that about an inch in depth of well-washed 

 sandj in which the plants should be planted, — over 

 the sand near an inch of the smallest stones or 

 pebbles ; minnows and sticklebacks are the best 

 fish to stock with, being the hardiest, living the 

 longest in confinement, and they agree well together. 

 I have minnows now that I have had at least two 

 years. They should be fed with animal food ; any 

 kind of cooked meat not fat ; two or three pieces to 

 each fish (about double the size of a pin's head) 

 each time of feeding. I feed mine about every five 

 or six days. Some minnows I have are so tame 

 they will take food from the fingers. I have kept 

 stickle-backs more than twelve months; the very 

 small ones do better and live longer than the large 

 ones ; some I have caught about half an inch long, 

 have lived until quite an inch and a half. A few 

 snails should be kept in the aquarium with the fish ; 

 Ihey assist to keep the water clear and eat the de- 

 cayed plants. They breed, and the young ones, and 

 also their spawn, or eggs, find food for the fish. 

 When they die they are eat by the fish ; there is 

 no fear of their contaminating the water. No doubt 

 fish will live a long time without any food but what 

 they find in the water, but they thrive much better 

 with occasional feeding. In my aquarium the 

 Avater has not been changed since May, 1863 ; every 

 month or two I put in about a pint to replenish what 

 it has lost from evaporation ; and it is now beauti- 

 fully clear. — Thomas Armstrong, Manchester. 



MICROSCOPY. 



Bull's-eye Condenser.— Will you allow me to 

 suggest a cheap and very effective condenser for the 

 microscope for viewing opaque objecls. I have tried, 

 I think, every kind made, and find this better than 

 most, and I think as good as some very expensive 

 ones. I use a glass globe about three and a half or 

 four inches in diameter, filled with clear spring 

 water, inverted upon an ordinary wine-glass. With 

 a series of them filled with various coloured waters, 

 I have had some very beautiful effects. JVIine cost 

 mc Is. — Thomas Armstrong, Manchester. 



Pollen of Evening Primrose.— I do not recol- 

 lect seeing the Evening Primrose named among the 

 flowers whose pollen grains form beautiful micro- 

 scopic objects, and would advise those of your 

 readers who take an interest in these matters, and 

 have not already a slide of it in their cabinets, to 

 mount one in balsam, and another as an opaque 

 object. The flower being so common there is no 

 difficulty in procuring it in most places. — E. G., 

 Mattock, 



On Stage Forceps. — Having been much incon- 

 venienced by the unsteadiness of tlie stage forceps of 

 the usual construction, I set my wits to work to 

 make a better ; and after some trials hit upon the 

 following, which appears to me so simple that any 

 one may make it for himself. The annexed diagram 

 scarcely needs explanation : A represents a piece of 

 wood ; B, a hole for the reception of C, the forceps- 

 holder, fastened by its screw ; D, the forceps, pass- 

 ing through a hole in the piece of wood and the 

 spring tube of the holder; thus the forceps have a 

 smooth rotatory motion on their own axis, by which 



any small object held therein can be viewed on 

 almost all sides. To fasten the forceps to the stage 

 I make a slit, E, near the bottom of the wood, which 

 slips over the slidhig-bar of the stage; by replacing 

 the wood by a metal plate, the forceps could then 

 be laid on the stage like a slide and the object 

 rotated, without going out of sight, as was often 

 the case with the old-fashioned forceps. I have 

 found the above to ansM'er admirably. For ex- 

 amining such things as flies' legs, heads, and pro- 

 bosces, with the binocular instrument, as opaque 

 objects, the effect is very good, and the investigation 

 can be made with much greater comfort and pre- 

 cision than with the old stage forceps.— .</. /. 

 Rotjcrts. 



