Bathythermograph Grids

A bathythermograpg grid is a transparent glass slide, marked with calibration lines of temperature and depth, that, when superimposed against a bathythermograph slide, makes it possible to read observed values of temperature and depth. This box contains 17 bathythermogarph grids, each in a plastic holder. In a wooden box designed to hold 50 slides; with handwritten notes, and a paper index pasted to the inside of the box lid.