Here's a closer detailed look at the new additions.
10c Dark blue
15c Olive brown
20c Yellow green
1927 Lindbergh's Trans-Atlantic Crossing #C10, Lindbergh Tribute
The world rejoiced when Colonel Charles A. Lindbergh completed the first solo transatlantic crossing aboard the Spirit of St. Louis, the single-engine plane he piloted on a non-stop, 33½ -hour flight from New York to Paris. To mark this historic event, the Post Office Department agreed to issue a special airmail stamp - the first time a living American was honored.
Both these stamps are similar in design and actually not very difficult to tell apart. The difference as mentioned in the catalogs is in the no of perforations. C12, the first stamp in the picture above is perf. 11 and C16 is per. 10 1/2 x 11. The perforations can be measured by a perforation guage, but as I dont have one yet, I just stick to counting the perforations using a regular scale and thats how I have identified these two apart. Simply measuring the no of perforation teeth between two cms of a regular scale does the trick. Simpler still, just place both the stamps on top of each other and if the perforations don't match you know you've got both these.
I have noticed one more difference in these two stamps and that is in the shade or density of the violet colour on both the stamps. The violet is lighter and less dense on the C12 as compared to the C16. Atleast this is true with my copies. Need to confirm this with another pair of these. Cool stamps though.
More Winged Globes, C17 & C19
8c Olive bistre
6c Dull orange
1935-1937 Trans-Pacific Issues #C20-C22
To improve contact with its Pacific Island possessions, the U.S. inaugurated airmail service from San Francisco to the islands of Hawaii, Midway, Wake, Guam and the Philippines. Mail was flown by Pan-American Airways aboard large seaplanes known as China Clippers, named for the 19th century ships that carried tea back to the U.S. from the Orient.Trans-pacific airmail service began November 22, 1935 as commemorated on stamp #C-20, the 25c stamp in the picture above, which bears this date.
# C24 - 30¢ Trans-Atlantic Winged Globe