KEEPING WARM 
Up until now you've been seeing less than 
what you paid for-30% to 50% less. Here 
at last is a mini that compensates for the 
distance between the eye and the eyepiece 
to give eyeglass wearers full field of view 
Wearing glasses, you get 30% greater field 
of view than with the best of other minis- 
300 feet at 1,000 yards as against 174 
feet at 1,000 yards. 
Though a pygmy in size, it performs 
like a giant. With all the magnification, bril- 
liance, clarity and contrast of its big 
brothers. Built to last a lifetime, it's guaran- 
teed to last a lifetime. 
Send for full color brochure showing 
and describing complete Zeiss line. Carl 
Zeiss, Inc., 444 Fifth Avenue, New York, 
NY 10018. I — | Biiins 
Carl Zeiss. Inc. 
Consumer/Optics 
West Germany 
A BREAKTHROUGH FOR 
EYEGLASS WEARERS. 
THE ONLY MINI THAT GIVES YOU 
FULL FIELD OF VIEW 
through a house, but pressure differen- 
tials and temperature stratification 
tended to create a very uneven distribu- 
tion of heat. Steam heat looked promis- 
ing for a while because it solved the 
problem of moving heat from where the 
fuel burned to where the heat was actu- 
ally wanted. The steam could be piped 
under its own pressure and then, on 
losing its heat, would condense back to 
water and return by gravity. Steam radi- 
ators, however, were noisy and exces- 
sively hot. With the development of 
small electric motors, heat distribution 
problems were more easily and comfort- 
ably solved. Small electric pumps could 
move warm water noiselessly through 
baseboard convectors, and electric fans 
could force warmed air to every corner 
of a building. In addition, these motors 
could be controlled with electric signals 
from thermostats so that a steady tem- 
perature could be automatically main- 
tained. 
By the early part of this century the 
technology of heating with mechanical 
systems had been worked out fairly well. 
But heating is only half of the climate- 
control problem and by far the easier 
half to solve. It is much simpler to 
generate and retain heat than to dispose 
of it. In hot, dry climates people have 
long depended on evaporation to dispose 
of unwanted heat, using systems of foun- 
tains, plants, and even permeable clay 
pots filled with water to cool and hu- 
midify the air. But in humid climates 
evaporation is greatly inhibited and ra- 
diational cooling to the night sky is also 
reduced. This made it nearly impossible 
to cool a place in hot, humid weather 
until the advent of air-conditioning tech- 
nology — a revolutionary step in climate 
control. 
About the turn of the century, Willis 
Carrier, an American engineer, hit upon 
a way to simultaneously dehumidify and 
cool air. He developed the somewhat 
paradoxical system of dehumidifying air 
by passing it through a spray of water. 
Based on the principle that cold air 
cannot hold as much absolute humidity 
as warm air, Carrier’s system passed 
warm humid air through a spray of 
chilled water. In this way, the air was 
cooled and forced to lose its excess hu- 
midity, which would then condense on 
the surface of the water droplets in the 
spray. By choosing how cold to make the 
water spray, it was possible to control 
exactly how much humidity would be 
left in the air. The air could be reheated 
to a comfortable room temperature, 
36 
