The Saalfield Publishing Company reprinted a number of Altemus juvenile series. Starting in 1934 books generally came boxed in sets of three.
Here is the information about the Meadow-Brook Series.

Meadow-Brook Girls Series #1356 Janet Aldridge
This series had two Saalfield reprint formats. All six of the original Altemus books were first published by Saalfield in 1934. The boxed sets had a random selection of three books. The later publications are 8.125 x 5.5. The earlier books are 7.625 x 5.25.

The later books are numbered #3757, #3758, #3759.

1. Under Canvas
2. Across Country
3. Afloat
4. In the Hills
5. By the Sea
6. On the Tennis Courts

Early boxed set
Later format reprints