by day

by day

 and by night
during the day; during the night. (Often used in simultaneous clauses for contrast.) By day, Mary worked in an office; by night, she took classes. Dave slept by day and worked by night.
References in classic literature ?
By day they worked under the rays of the scorching sun; by night, under the gleam of the electric light.
All her old sorrows had come back upon her, augmented by new fears and doubts; by day they were ever present to her mind; by night they hovered round her pillow, and haunted her in dreams.
So they were soon fat and there was an end of them, but I grew leaner day by day, for I ate but little, and even that little did me no good by reason of my fear of what lay before me.
How like your voice has grown to his, but more tremulous, and both so solemn, so unlike the voice of either of you by day.
In drawing her up from the world, he was day by day being himself dragged down towards it.
Based on the needs assessment conducted by ACA in the fall of 2003, several critical needs were expressed by day camp directors.
When stocks fall, one strategy used by day traders is the "Lizard Reversal.
By being a day trader, he figures it will be easier on him since he'll sell all his positions by day end.
Initiated by Day, JSR 170 is the Java Content Repository (JCR) standard for the enterprise content management industry.