5,000 tons. The notable increase in the size of vessels, especially on the coasts and Great Lakes, has been an important factor in reducing transportation charges. As a general rule it can be said that the larger the vessel, of the same type, the lower will be the cost of carriage. The size of vessels is determined in large measure by the depth of channels and harbors and the terminal accommodations, and adequate improvement of these is necessary to secure the use of the largest and most economical vessels. On western rivers an unusual feature of recent development has been the decrease in the size of steam vessels, along with a noticeable increase in their number. This is due mainly to the change to a barge-and-towboat system and to the increasing use of small gasoline boats, which are included with steam craft. It is somewhat surprising that there are no official records of the maximum draft of vessels, and thus no means of determining the extent to which channels of a given depth can be used by vessels now built. TABLE 12.-NUMBER AND TONNAGE OF DOCUMENTED SAILING AND STEAM VESSELS OF THE UNITED STATES IN 1907, BY SIZE AND BY DISTRICTS. [Report of the Commissioner of Navigation, 1907, p. 203.] Total....5, 802 1,563, 789 61, 298 1, 440 467, 709 30 13, 933 1, 873 2, 044, 553 1, 486 157, 338 10,637 4, 248, 620 a See note b, Table 14. CENSUS STATISTICS.-The documented vessels do not, however, include all the vessels in the United States. The United States Census reports on transportation by water aim to include, in addition to documented vessels, all undocumented craft of over 5 tons net register, and these reports are the most complete records available. Table 13 presents a summary of the Census statistics by districts, for 1889 and 1906, showing the number and tonnage of steam and gasoline, sailing, and unrigged vessels. The most striking difference from the statistics of documented vessels is the much larger proportion of unrigged vessels, such as barges and canal boats. These are of especial importance on the Mississippi and tributaries and on the Atlantic and Gulf coasts. From this table it also appears that the greatest absolute increase in tonnage from 1889 to 1906 was on the Atlantic and Gulf coasts, but the greatest relative increase was on the Great Lakes (160 per cent), and on the Pacific coast the total tonnage increase was 133 per cent. On the Mississippi River and tributaries there was a notable decline in steam-vessel tonnage, but this was more than counterbalanced by the increase in the tonnage of unrigged craft. TABLE 13.-UNITED STATES CENSUS STATISTICS OF VESSELS AND VESSEL TONNAGE, 1889 AND 1906, BY CLASSES AND BY DISTRICTS. [Compiled from United States Census Report on Transportation by Water in 1906.] ries...... Other inland waters... 192,974 146,227 Total.. 972 1,435 163 337 5,603 9,927 1,710,073 4,059,521 7,945 7,131 1,675,706 1,704,277 25 14 1,925 518 ries...... Other inland waters.. Total.. 6,328 8,187 a3,171,636 a4,265,740 7,300 9,622 3,364,610 4,411,967 6,387 1,789 a 975, 481 a 237,466 6,575 2,140 996,629 259,491 16,937 20,263 4,973,356 7,129,631 30,485 37,321 8,359, 135 12,893,429 a On western rivers and other inland waters the size of undocumented barges and other unrigged craft is usually given in capacity tons instead of measurement tons; and while these figures are given by the Census as "gross tonnage," it seems probable that they are in large measure "capacity tonnage." DECLINE OF STEAM-VESSEL TONNAGE ON WESTERN RIVERS.—Table 14, compiled from the reports of the Commissioner of Navigation, shows the documented gross steam tonnage of the Mississippi and tributary rivers, by years, for a period of twenty years. The tonnage shown is classified according to size of vessels as follows: Class A includes vessels of from 5 to 100 tons, Class B from 100 to 500 tons, Class C from 500 to 1,000 tons, and Class D from 1,000 to 2,500 tons. TABLE 14.-DOCUMENTED STEAM VESSELS ON WESTERN RIVERS, 1888-1907, BY SIZE. In addition to the total shown, 2 vessels of 2,525 tons gross each were permanently documented in 1907. Due to the fact that they do not operate on the western rivers, the number and tonnage are omitted from this table. The company owning this craft was incorporated under the laws of the State of West Virginia with statutory office at Wheeling, W. Va., from which point the documents were issued. The vessels, which are steel dredges, operate on the sea board. The table just given shows a decrease in the total gross tonnage of 61,748, or 29 per cent, on June 30, 1907, as compared with June 30, 1888, while the vessels have during the same period increased in number to the extent of 362, or 32 per cent. Each of the four classes into which the vessels are divided, excepting Class A, has decreased as to both number and tonnage. Class D, which comprises the largest steamers, consisted of 26 vessels in 1888, with an aggregate gross ton nage of 33,330. In 1907 this class had been reduced to 8 vessels, aggregating 11,057 gross tons, a decline of 70 per cent in number and 67 per cent in tonnage. Classes B and C suffered a like decrease, but not to the same extent, Class C having been reduced 28 per cent in number and 32 per cent in tonnage, while Class B was reduced by 33 per cent in both number and tonnage. The smallest steamers, those of Class A, show an increase of 51 per cent in number and 27 per cent in tonnage. As shown in the following table, this class of vessels has been further subdivided, showing that the only appreciable increase in steam tonnage, including gasoline boats, on western rivers, is found among vessels of less than 50 gross tons. TABLE 15.-DOCUMENTED STEAM VESSELS OF LESS THAN 100 TONS, ON WESTERN RIVERS, 1889 TO 1907. The total increase for both classes for the 19 years covered by the table was 568 in number and 9,711 in tonnage. An examination of the first two columns of the last table shows, with respect to vessels of from 5 to 50 tons, an increase during the first ten years of 1,170 tons and 65 vessels, a rather insignificant amount as compared with an increase of 5,538 tons and 467 vessels which occurred during the remaining nine years. The third column in the table shows but a slight increase in vessels of from 50 to 100 tons during the entire nineteen years. There thus appears to exist a condition on the Mississippi and its tributaries differing from that on the Great Lakes, the coasts, or in point of fact on the world's waterways in general. On the Great Lakes sailing vessels have been largely eliminated and replaced by steam freighters of immense burden. On the coasts schooners have decreased in number but increased in size. 56849-PT 1-09-10 The contrast between these conditions on waterways generally and the decrease in tonnage and increase in number of steam vessels on western rivers is due largely to the disappearance of many large packet steamers and increase in small gasoline boats. This situation may be caused in part by the limited depth of water in the rivers, which discourages the building of large steamboats, but it is also due in part to an important tendency in the methods of carrying traffic on the rivers. The increase in the number and tonnage of barges on western rivers shows that the system of barge towing is increasing in relative importance, and this is true not only for the carriage of bulk commodities but also to some extent for package freight. On this account the decline in the total tonnage of steam vessels does not indicate clearly the tendency in regard to the volume of traffic. The available information as to the latter point will be considered in Part II of this report. II. TYPES OF VESSELS. Floating equipment presents a striking contrast to the rolling stock of railroads in the great variety of forms and types that have developed in transportation by water, and the adaptation of particular types to local conditions and to special classes of traffic. This adjustment of vessel types is an important factor in the development of water transportation; but it also reduces the mobility of the floating equipment, since vessels adapted for one route or one class of traffic can not be so economically used for others. Vessels may be classified according to method of propulsion into sailing vessels, self-propelling vessels, and unrigged craft. They may also be considered with reference to the materials of construction, as wooden, iron, steel, or composite vessels. They may be grouped according to the character of occupation, as freight and passenger boats, tugs and towing vessels, ferries, etc., or as regular-line boats, bulk cargo vessels, and "tramps." Within each of these classes there are special types with reference to the character of the water route and the nature of the traffic. Some account of the main types of vessels and the growth and decline of tonnage will be given in the following pages. Section 3. Steam and motor vessels. Steamboats were first made practicable in the first decade of the nineteenth century. On the western rivers there soon appeared the well-known flat-bottom, stern-wheel steamboat, adapted to the shallow waters of those streams, the design of which has not greatly changed for half a century. Steam vessels did not come into active use in the open-sea trade until after 1830. The screw propeller was |