• THERMAG semi-vacuum glass blocks, with "Magnalite" lenses give complete 4-way light diffusion through an entire room. Total solar heat transmission per square foot of skylight area is under 50% by test. Airtight construction virtually eliminates heat loss.

• THERMAG's rigid, insulated reinforced concrete grid construction is designed to withstand all snow loads and foot traffic. THERMAG's smooth surfaces clean easier. Its design and insulation guard against any chance of condensation.

• THERMAG's even diffusion of mellow white daylight over side room areas keeps skylight aeras at a minimum. The soffit is highly ornamental. For details, see Sweets. For prompt engineering service without obligation, write direct to 2139 West Fulton Street, Chicago.

Light Up—the AMERICAN Way!

DAYLIGHT ENGINEERS

AMERICAN	3way-Luxfer	PRISM CO.
CHICAGO		NEW YORK