This three book series is quite uncommon. It was published in 1918.

The titles are:
1. Peep of Day
2. Line Upon Line
3. Precept Upon Precept

For more information about the series see: http://henryaltemus.com/series/series140.htm

Today I am adding the dust jacket picture for book #2 in the series. All three books were jacketed with the jackets matching the front cover.