ENGINEERING 
623.6 Military roads, bridges and bildings 
From the special point of view of military servis. For construction in general 
see 690.1 and 721; for bridges, roads and railways see 624 and 625; for seacoast 
walls, see 627 Hydraulic engineering 
Military bildings 
Duplicating 725.18 for military engineers. Libraries should use 725.18 and 
leav 623.61-.614 vacant; for construction of fortifications see 623.1 
61 
611 
O12 
613 
Barracks 
Military establishments 
Groups of bildings forming a unit; e.g. military schools, army posts 
Magazines 
Military roads and thorofares 
See also 625.9 Construction of road: 
Military railways 
See also 625 Railway construction 
614 
62 
612 
631 
632 
033 
634 
6c 
Destruction of tracks 
Military bridges 
For permanent bridges see 624 
Pontoon bridges 
Trestle bridges 
Other temporary bridges 
Bridge material 
Military signals Aeronautics, etc. 
Special military applications of science 
Military topografy 
Special processes and instruments. See also 526 Topografy in general 
Photografy 
Reproductiv processes applied to military art. See also 770 Photografy 
72 Signaling Military telegrafy 
731 Visual signals: heliografs, searchlights, etc. 
732 Military telegrafy 
Both wire and wireless. See also 621.382 and 654 Telegrafy 
733 Military telefony 
Both wire and wireless. See also 621.385 and 654.6 Telefunv 
Military aeronautics 
For principles see 533.6 Aeronautics; for construction of airships see 629.13 
Class here only military utility 
Machines lighter than air 
Free balloons 
Dirigible balloons 
Cantiv balloons 
051 
652 
653 
6354 
66 
4 
741 
742 
743 
744 
745 
746 
749 
ne 
Machines hevier than air: aeroplanes 
Other topics 
Military sanitation 
Camp sites: soil, water, drainage. ete. Por personal hygiene see 6132.6