>Congrats to Bill and to Dan. I get the Old Mill Disney reference. I like this story so the answer is long. They rode the Sanger lumber flume from Millwood camp, CA in the Bigtree country to Sanger, California, in the San Joaquin Valley. The estimated dimensions of the water flume itself were 48” wide at the top, 16” wide at the bottom, and had 32” sloping sides. In pictures of other flumes the water level was within 6” of the top. The descent was 4,737 feet, 4,300 of it in the first 13 miles. In some places the drop was 330 feet per mile and later, estimated speeds were determined to be approaching 70 miles an hour.
(Note: For us Easterners the Niagara River is about 56 kilometers (35 miles) long and includes Niagara Falls along its course. The total drop in elevation along the total river is 99 meters (326 feet). The Upper Niagara Rapids drop only 15 m (49 feet) in the 800 m (½ mile) before the Falls. Below the falls the gorge is world famous for its rapids. The width of the Whirlpool Rapids Gorge narrows to approximately 150 yards (137m). The rapids generated here are amongst the wildest and most formidable in the world (class V-VI). The depth of the Whirlpool Rapids is 10.7 meters (35 feet) and the speed of the water at the Whirlpool Rapids is 35.4 kilometers/hr (22 mph). The speed is the result of the narrow width of the gorge as well as the rapid descent of the river. The descent is 15.8 meters (52 feet) in less than 1.6 kilometers (1.2 miles).
The lumber flume was made of 9 million feet of clear, knot free redwood and was used to transport 250,000 board feet of lumber down the flume per day. The flume cost when originally built was $300,000. They made the trip in a “boat” of lumber and ran “like the milltales of hell”. Millard merely sat on a crate and the photographer on a block of wood. According to the account I read, they traveled over cantilevered poles on cliff sides “which hung by a miracle”, dodged branches, avoided skewering by large splinters, and were propelled over narrow and high trestle bridges. Leaning to dodge an overhanging branch Millard fell into the trough. He was bruised and abraded but was able to get back aboard with the aid of the photographer on a slower section to complete the journey. He was shaken but stirred. “One feels that to make such a voyage every day would in time fill even the commonest of men with the abandon of the Gods.” There was no mention of the time it took to complete the run or how long a head start they had before lumber began following them down.