THE GUIDE TO NATURE 
130 
A SEVEN-FOOT SPIRAL CAVITY IN AN APPLE 
TREE PROVES THE VALUES OF 
“FLEXIFILL.” 
It fills the cavity completely. It keeps 
out moisture and air. It preserves the 
wood on the inside of the cavity and 
prevents the further decay back of the 
filling which so often happens behind 
the concrete fillings. 
Every lover of trees will hail with 
delight Mr. Bartlett’s long step for- 
ward. His new compound is rapidly 
making concrete look as much out of 
date as the mixture of lime-rubbish. 
wood ashes, sand and cow manure. 
We advise our readers to send to 
The F. A. Bartlett Tree Expert Com- 
pany, Stamford, Connecticut, for fur- 
ther particulars of this wonderful in- 
vention. 
Not Using Spectacles With a Micro- 
scope. 
BY FRANK T. MYERS, VENTOR, NEW JERSEY. 
I wear spectacles but do not use 
them when working with the micro- 
scope. I have also a number of friends 
doing microscopical work but they, as 
far as I know, never use spectacles 
while actually looking through a scope. 
The eye point of the majority of oculars 
is too close to the eye lens to make it 
at all convenient and I am a firm be- 
liever in having the pupil of the eye 
as close to the eye point as possible in 
order to get the best results. Then, by 
the addition of another lens (which is 
all spectacles are, after all) the delicate 
corrections of a good optical combina- 
tion. especially in the higher powers, is 
upset. Personally, I never miss spec- 
tacles in looking through the micro- 
scope, as the necessary adjustments 
can be made by focusing. 
Coal Preserves Ice. 
BY C. I). ROMIG, AUDENRIED, PENNSYLVANIA. 
A few feet of drifted snow were by 
a gale covered with about four inches 
of coal dust, and up to June tenth it 
was possible to dig snow where the sun 
was shining unbearably hot for most of 
the day. 
Standing on this spot a few days ago 
I heard a blast and a piece of coal 
struck the ground two feet from my 
heel, the coal having traveled for about 
five hundred yards. I learned that 
workmen were blasting ice and snow 
so that the steam shovel could dig a 
cut through old rock banks deposited 
in winters more than twenty years ago. 
In this way ice and snow thirty to' 
fifty years old are often dug up. These 
might keep forever if not disturbed. 
The national forests of Alaska, un- 
der the methods followed by the For- 
estry Service, can continue indefinitely 
to produce a million and a half tons of 
paper yearly. 
