I have a 1937 White sewing machine. (Knee Operated) In one of the drawers on the right side of the cabinet there is a small shelf with 2 holes that hold 2 glass bottles. The bottles have black tops with a small hole in each. I would like to know what the bottles are for. Someone said 'ink wells', but the holes are too small. There is a piece on the tops that slides to open or close the holes. Anyone know what they are? If not, I guess ink wells could be the right answer. Thanks.

Could the bottles be for oil?