8 BULLETIN" 194, U. S. DEPARTMENT OF AGRICULTURE. 
were those used by the writer and his assistant, Mr. Ernest C. For- 
tier. Where those used by his associates were essentially different, 
the fact is mentioned. 
EQUIPMENT. 
Tapes. — Linear measurements for length of canal tested were made 
with a high-grade steel tape, 100 feet long, graduated to tenths of a 
foot. This tape was also used to determine widths for current-meter 
measurements for canals more than 25 feet wide and cross-section 
data for canals more than 50 feet wide. For canals under 25 feet in 
width the measurements of widths in determining the discharge were 
made with a small steel tape, 25 feet long, graduated to hundredths 
of a foot. For taking cross sections on canals less than 50 feet in 
width a 50-foot cloth tape containing strands of wire was used. 
Level. — The writer used a new 18-inch Berger engineer's wye level, 
equipped with a bubble whose sensibility was rated at 10 seconds of 
arc for 1 division of scale equal to one- tenth of an inch. The bubble 
vial was 6.5 inches long. The telescope power was 35 diameters. 
Rod. — A new Philadelphia rod, equipped with rod level and with 
vernier reading to thousandths of a foot was used in the determina- 
tion of the fall between the bench marks at the upper and lower ends 
of the reach tested. 
Current meters. — Two new small Price cup current meters were 
used. They were identical in construction, of the combination type; 
that is, each meter was so equipped that a single or a penta head could 
be used. The single head records each revolution of the meter and 
is adapted to water flowing up to about 5 feet per second. The penta 
head records each fifth revolution of the turbine and is used in high 
velocities. Both of these meters were rated on both rod and cable 
by the United States Bureau of Standards at Chevy Chase Lake, Md. 
They were carefully rated, as it was understood that they would be 
used for research work. One of these meters was used constantly, 
throughout the summer, the other one being very carefully cared for 
and rated against the one in constant use at intervals throughout the 
summer, so that any variation of the rating curve could be detected 
early. At the end of the season the one in use was again rated by the 
writer, at Calexico, Cal., and it was found that if any change had 
taken place it was too small to necessitate a change in the table. 
The meters could be used on either rod or cable. Eight 1-foot sec- 
tions of rod, graduated to tenths of a foot, were carried. 
When the meter was used on a cable the lower 18 inches of cable 
was replaced with a section of strong piano wire, with a swivel har- 
ness-snap connection to the hanger rod attached to the meter. 
Two 6-pound lead torpedo weights were carried, while it was found 
necessary to use 24 pounds of lead in the New York Canal, with veloci- 
ties up to 6.6 feet per second in depths of 6.62 feet. 
