Horace Brock (1908-1981) was an early Pan Am pilot and navigator and subsequently an executive. Scion of a wealthy Philadelphia family, he attended Yale and graduated from Harvard Law School, but never practiced: instead, on graduation, he signed up for the Army Air Corps as an aviation cadet. He was eventually commissioned as a 2nd lieutenant and bomber pilot, but resigned to join Pan American's Caribbean Division in 1935 as an "apprentice pilot." At Pan Am, he was cross-trained as a navigator, radio operator, and licensed mechanic, flying Caribbean routes as navigator and first officer. In April 1937, he was transferred to the Pacific Division, flying the Martin M-130 and Sikorsky S-42 mostly as a navigator. In 1939, he transferred to the Atlantic Division, flying the S-42 and the Boeing 314, as first officer, and later, as Pan Am styled it, "Master Ocean Pilot." He was eventually ran Pan Am's Atlantic Division. In 1978, we wrote his memoirs, "Flying the Oceans," (Stinehour Press), which is filled with interested and detailed stories about ocean navigation in the 1930s.
One such story relates to charts. The story appears in the context of flying along the Brazilian and Venezuelan coasts in 1935-1936.
"Our jobs as pilots involved special problems. There were, of course, sailing charts, hydrographic charts, and coast charts issued by the U.S. Coast and Geodetic Survey. These ocean charts were of little use due to lack of details of the shores of the adjacent land. We were reduced to maps issued by the National Geographic Society and school-book atlases. Mostly, we drew in prominent features of terrain as well as courses and distances on any maps we could obtain. My mother used to send me ones she got at a map store in Philadelphia. The USC&G chart [Actually Hydrographic Office-adr] which I used on this first Para [Brazil] trip was only a strip cut from the full chart. I noticed on it a landmark which said "Big Tree," on the dotted shore shown between the Orinoco and Marajo Island. Obviously there were no trees along this coast, only mangrove swamps and no identifiable shoreline for hundreds of miles. When I got to Miami, I looked for and found a copy of the entire chart (we always cut them into strips as they were easier to handle in the cockpit) and promptly sought the lower, left hand, bottom corner where the legend was, and under it, in fine print, the source was given as "From Surveys by Magellan."