lathes

Looks like a metal lathe; the cage device probably encloses the drive motor to keep fingers, arms, etc. from getting caught or being shocked.

This is a (near) duplicate of an existing photograph in the Harris & Ewing collection of The Library of Congress.
C. W. (Clarence Wirt) Hecox (1872-1951), an instructor in the machine shop at McKinley Training School, Washington, DC, supervising a student using a lathe in the manufacture of practice shells for the U.S. Navy. The basket weave dome is a venting cover for the lathe motor (in addition to the other safety features Bolobilly said).
– excerpted from original caption, with information added. [1] [2]


As a bonus ;) it appears to me like the student in this photograph is also featured (2d from left) in another photograph
in the Keystone View Company collection of The Library of Congress. "Doing their bit - students of McKinley Manual Training High School, Washington, D.C., with 4-inch shells they have made."

Thanks Bill Forbes for identifying the machine. Also, thanks Pixel Wrangler for locating near duplicate image that has a good caption. We'll update this photo's catalog record with this information.

It is often overlooked how important railroad companies were as manufacturers. Their own shops were industrial sites of considerable scope and sophistication.

Fantastic photographic portrait - the light is stunning.