STATE GEOLOGIST. 59 
‘the stone and coarse gravel and the excess of wet mortar will run next 
the form. Thus when the mass is set and the form removed the exterior 
will be smooth and waterproof. This method is cheaper than the two 
inch facing and equal in durability and appearance. 
PROTECTION TO BRIDGE METAL. 
Mr. J. M. Newhouse, carpenter foreman for the Columbus Terminal 
of the Pennsylvania railroad, has used Portland cement with oil and red 
lead to coat the metal work of the High Street Viaduct. A test section 
was coated early in 1900 and now after four years wear seems to be in 
excellent condition. Where it has been cut out for examination the metal 
is perfectly bright. The entire eastern section of the viaduct owned by 
the Big Four Railway Company was covered with this cement coating 
in 1900 and 1g9o1 and is still in excellent condition. The outside of the 
eastern-most girder with the supporting posts show expansion cracks 
in the coating wherever the sun can strike the paint, but at no point does 
the coating seem to be loosened by this cracking. Upon cutting into 
the metal it does not appear to have sustained any corrosion. This coat- 
ing was applied with trowels and is about 4% of an inch thick. It required 
much care’and time in spreading it, especially around the rivet heads. 
Small friction or troweling cracks would occur whenever hasty work 
was done. These cracks would have admitted water and allowed the rust- 
ing to proceed, therefore great care was used to put on a perfect coat. 
The steel work had been cleaned by the sand blast, and painted the year 
before, so that only hand cleaning was done before the mortar paint was 
applied. The cost of this coat, including the hand cleaning of the metal 
work and the cost of materials and applying them was eight cents per 
square foot. © 
The place is a particularly trying one on metal work, as the lower 
flanges of the girders are only about two feet above the smoke stacks of 
the passing engines. Practically all the traffic, passenger and freight, 
entering and leaving the Union station pass under this viaduct. Ordinary 
paints are cut out in a very short time and unprotected metal work soon 
corrodes through %4 to 3 inch members. If this cement coat lasts as it 
promises to do, it will be well worth the additional cost. The officials 
said that it cost from one quarter to two-thirds more than the paints 
usually used. The life of ordinary paints is not much over three years, 
and under the trying conditions of this particular place would not prob- 
ably exceed eighteen months to two years at the longest. 
Mr. Newhouse gives the following directions for the cement coat: 
12 pounds of red lead. 
32 pounds of Portland cement. 
2 pounds of Japan.. 
Add sufficient linseed oil to make, when thoroughly mixed, a soft 
putty like mixture. Apply with a trowel, upon thoroughly cleaned metal. 
