Mr. Gilbert Grandy lived in Dundee, a village in west-central New York State.

Seneca Lake, one of the Finger Lakes, is four miles east of Dundee.

https://en.wikipedia.org/wiki/Dundee,_New_York

In July of 1909, Gilbert received a postcard from D. B.

D. B. mailed the greeting from Amsterdam, a city on both sides of the Mohawk River in central New York.

https://en.wikipedia.org/wiki/Amsterdam,_New_York

The face of the postcard is a drawing of a quartet playing cards.

The game may be poker, as the players have colored chips beside them.

The young man and young woman in the center appear to be studying their hands, but the two opposite one another are exchanging a sly look.

The caption explains, “Chips that pass in the night”.

This play on words may relate to a chance encounter or to a missed opportunity.

“Ships that pass in the night”, the original reference in a poem by Longfellow, usually refers to a brief and unexpected encounter by participants who may never meet again.

There may be a suggestion of mystery or regret.

https://en.wiktionary.org/wiki/ships_that_pass_in_the_night

Here, the “passing” seems to be a tacit acknowledgement of one another without the exchange of words – possibly in the payment of chips.

This silent signaling may have been a common occurrence when strict rules of address or familiarity were observed.

On the reverse, D. B. reports that the night shifts continue without a definite end.

The sender is well, and “having a good time”.

One hopes that D. B. and Gilbert had success in cards or other social pursuits and that their romantic adventures were rewarding.