138 
THE ^OUNa {SCIENTIST. 
A quantity of baruacles remaining still 
unused, suggested further designs, and I 
procured some long and short cone-shaped 
pieces of pumice stone, that resembled 
stalactites, and covered them with barna- 
cles and algee. In floating these on the 
surface, my tank had the appearance of a 
grotto, the effect of form and light and 
shade being quite novel. The inquisitive 
" shrimp " [Palamenies vulgaris), and quaint 
little hermit crabs [Eupagurus longicarpus), 
were soon scrambling over the rocks, clean- 
ing the barnacles to immaculate whiteness. 
To support this increase of animal life, 
more oxygen was necessary, and more ulva 
( Ulva laiissima) was added. 
The barnacles did not feel at home imme 
diately, and the little fairy-like hands were 
not at work for two days. Then the reach- 
ing and grasping began, and so rapidly did 
they devour the minute animal and vege- 
table life contained in the water that at the 
end of a day the water was as clear as crys 
tal, and of a light blue color. 
Suddenly, one day, a piece of pumice stone 
began to revolve, and my first thought was 
that a prawn or hermit crab was somewhere 
at work on it; then it seemed as if, from 
some unknown cause, an imperceptible cur 
rent of water caused it to turn; but I was 
finally convinced that I was in error. I 
took the piece of pumice out overnight 
and, assisted by a scientific friend, made i 
more thorough examination. Placing the 
stone in the tank next morning, it remained 
motionless, and I concluded that the myste- 
rious power had departed or was destroyed. 
The clearness of the water, and inactivity 
of the barnacles suggested "feeding time," 
so I ground three small oysters into a paste, 
diluted with sea water, and dropped it 
slowly into the tank. Instantly all the bar- 
nacles appeared in motion, and three pieces 
of pumice stone began revolving rapidly. 
The mystery of the moving stone was 
plain; these three pieces were of nearly 
perfect cone-shape, and well balanced in 
the water. The barnacles had been ce- 
mented on the cones with their cirrhi, or 
hands, nearly all pointing one way, so that 
when feeding they struck the water with 
their rapidly moving hands, causing the 
cones to rotate. 
I determined to mystify some of my: 
scientific friends over this new motor, sa 
preparing a carefully balanced and turned 
cone, I cemented the barnacles in nearly 
concentric circles, with their cirrhi pointing 
one way. At the top of the cone I dug out 
a small reservoir, and from this I chan-l 
neled four gutters extending to the circum- 
ference of the base of the cone. In this.! 
reservoir I placed a quantity of diluted 
oyster paste, which slowly worked its way 
down the gutters and dripped into the 
water, causing the barnacles to work rapidly. 
To hide away the reservoir and oyster 
paste, I draped ulva over the base and part i 
way down the sides, also using small fronds- 
and pieces of seriularia arg&ntia, delesseria, 
enieromorpha and chondrus crispus. All 
combined gave to the cone the effect of a 
beautiful mass of marine life. 
Another curious fact about this pumice 
stone cone was that during one very cold 
night the surface water in the tanks froze i 
over, the low temperature of the water | 
causing the air contained in the pores of 
the pumice to contract. This allowed the 
water to enter the pores of the stone, caus- 
ing it to become heavier than the water, 
and sink to the bottom of the tank. When 
the temperature of the water rose again, 
after the sun had shone on it for a few 
hours, the air in the stone expanded and 
floated it up again. 
This moving stone was always a source of 
interest and mystery to my friends. Th© j!i 
barnacles lived over a year, slowly inoreas- 1 
ing in numbers. A. W. Egberts. 
— The latest novelty is a "barometer 
handkerchief." The design printed on it 
represents a man with an umbrella. In fine' 
weather the umbrella is blue, in changeable 
weather gray, and in rainy weather white. 
The secret lies in printing this design in 
chloride of cobalt; but the first washing 
removes this sensitive chemical, and de- 
stroys the barometric properties. 
