SHELL n.
or of a steam boiler, forming a case to contain the water and steam, often inclosing also flues and the furnace; the barrel of a cylindrical, or locomotive, boiler. -- Shell road, a road of which the surface or bed is made of shells, as oyster shells. -- Shell sand, minute fragments of shells constituting a considera…
SPECTRUM n.
ffects, as in photography. These, in the usual photogrophic methods, have their maximum influence at and beyond the violet rays, but are not limited to this region. -- Chromatic spectrum, the visible colored rays of the solar spectrum, exhibiting the seven principal colors in their order, and covering the central and…