This girl wears a long or 7/8ths coat to cover her riding breeches.
A woman on horseback had formal and informal clothing choices in 1910. This riding habit in the Victoria and Albert Museum was made by a leading London tailor/designer in 1911:
London Society Fashion is beautifully illustrated with garments from one young lady’s wardrobe: Heather Firbank. Read about the surprising life of Heather Firbank and see some of her designer clothing at the blog of Tessa Boase. Click here.
It’s possible that the illustrator of the magazine was more interested in the graphic possibilities of white than in accuracy, but Delineator did feature patterns for women’s riding habits in 1910.
I find it interesting that this teenage girl is riding astride, while the adult woman shown in April is riding sidesaddle.
The riding coat and skirt for adult women (up to size 42 bust) were sold separately:
Delineator, page 304, equestrian skirt detail; April 1910:
If you can figure out how this skirt appears very full (as in top image) and very narrow (as here,) you are way ahead of me. But then, I know nothing about riding sidesaddle! However, The Vintage Traveler shared this photo from a 1903 sports book. [Link added 2/27/19.)\]
Is it possible that she is wearing long underwear instead of riding breeches under the skirt? In that case, she will not be safe from embarrassment if she’s thrown. At any rate, no breeches are included in the pattern.
The boy shown riding a donkey is not actually dressed for riding — he is probably at a beach resort where donkey rides were a seaside attraction. The sailor suit in many variations was standard clothing for boys.
The swastika is an ancient symbol with religious meaning for people in India and for Native Americans. It’s used facing both directions on the back of the sailor collar. In 1910, it had no association with Nazis.
Here is my uncle, Harris Barton, in a sailor suit His father was a tinsmith, or plumber. (It might be my Uncle Mel, born a few years later….)
(Yes, my uncle, in spite of those luxurious curls!) Harris was born in 1894.