The Postmaster General's report for the year ending June 30, 1910, gives a clear conception of its magnitude. He showed then that there were 176 full railroad post-office lines, manned by 1,736 crews of 8,332 clerks. There were also 1,392 compartment railroad post-office lines--lines in which a portion of a baggage or smoking-car is partitioned for the sole use of the postal service--manned by 4,085 crews of 5,407 clerks, 18 electric car lines with 20 crews and 22 clerks, and 55 steamboat lines with 98 crews and 86 clerks. Of the cars built for the exclusive use of the railroad mail service, 1,114 were in use and 206 held in reserve, while 3,208 of the compartment cars were in use, 559 of these being held in reserve. In addition, the Post-office Department operates 25 trolley mail-cars. Great progress has been made in the substitution of steel mail-cars for wooden ones--a real step forward when one pauses to consider the dangerous position in which the mail-cars are placed in most trains. The records of the Post-office Department are filled with stories of heroism on the part of mail-clerks in saving, both the extremely valuable merchandise that is given to their care, and vastly more valuable human lives. The list of the post-office employees who have met death while on duty in the railroad mail service is not a short one. But the railroads are coöperating with the Government in giving the finest type of steel cars to its mail service,--sixty of these are already in use on the Pennsylvania system,--for, as we stated at the outset of this chapter, the transportation of Uncle Sam's mail is no slight function of the modern railroad. The big operating men across the land are constantly bending their heads with those of the post-office officials toward the betterment of that transportation. CHAPTER XXIV THE MECHANICAL DEPARTMENTS CARE AND REPAIR OF CARS AND ENGINES--THE LOCOMOTIVE CLEANED AND INSPECTED AFTER EACH LONG JOURNEY--FREQUENT VISITS OF ENGINES TO THE SHOPS AND FOUNDRIES AT ALTOONA--THE TABLE FOR TESTING THE POWER AND SPEED OF LOCOMOTIVES--THE CAR SHOPS--STEEL CARS BEGINNING TO SUPERSEDE WOODEN ONES--PAINTING A FREIGHT CAR--LACK OF METHOD IN EARLY REPAIR SHOPS--SEARCH FOR FLAWS IN WHEELS. To care for its rolling-stock the railroad creates two distinct functions of its business. All the care of its permanent way, including tracks, tunnels, bridges, comes under the control of the Maintenance Way Department. Similarly, the Mechanical Department assumes control of the cars and engines, sees to it that each is maintained to its fullest efficiency, both by care in daily service and by certain visits to the shops at regular intervals, for repairs, reconstruction, and painting.