Digital Library Search
![Figure 49 ship4423.jpg Figure 49](/sites/default/files/styles/max_1300x1300/https/s3.amazonaws.com/s3-east-testmedia-noaa.woc.noaa.gov/dam/Photos/legacy/pl23_ship4423.jpg?itok=VLBHRTZy)
Description
Figure 49. Fery refractometer, an instrument first suggested by Julius Hilgardof the United States Coast and Geodetic Survey to measure the density of seawater by relating the index of refraction of a liquid to its density. Theinstrument shown was developed by the Frenchman Charles Fery in 1891. (Image credit: Oceanographic Museum of Monaco | Y. Berard)