periscopes are used to find out what about objects
microscopic density location weight Light energy observe it age
A B C D E F G H
Periscopes are still useful, despite the sonar and electronic sensors of modern submarines.
Periscopes are used to find the location of objects
periscopes are used to find out what about objects (A) microscopic (B) density (C) location (D) weight (E) Light (F) energy (G) observe it (H) age