an optical device for viewing objects below the surface of water.
Origin of hydroscope
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for hydroscopicity
Historical Examples of hydroscopicity
How does the water content of some foods vary with the hydroscopicity of the air?Human Foods and Their Nutritive Value
any instrument for making observations of underwater objects
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012