I found a double sided bottle stamped "THE Eureka", Made in England with TABLESPOONS printed on the side with measuring notches. The bottle is boat/banana like, sits flat on a table and measures 7 1/2" Long x 2 3/4" Wide.
You've found a nice early nursing bottle. One end is for the nipple tubing and the other side is for a vent. Very nice find! My wife at one time had one of the largest nursing bottle collections in the United States.