The log cabin Democrat., 1916-03-31

of the latest geologic knowledge and the suggestions of the commission of scientists that lately came to the canal. Prof. J. K Mead, a geologst from the University of Wisconsin, who has made a specially of just such eX- periments as were suggested, was en- gagged to come to the canal and assist MT. Macdonald with his very special knowledge of his latest development of geological work.
 What Experiments Prove.
 The experiments Messrs. MacDon aid and Mead have been making prove that the rocks that have been sliding contain about 30 per cent, by volume, of water, very large amount. The rocks that are moving toward the channel of the canal are so broken up that they have had every opportunity to drain and to lose their water by evaporation. Notwithstanding these conditions, these rocks, as these ex- periments prove, have only about one half Of 1 per cent less water than the rocks of the same class that were ex- amined after they had been submerged in the canal for months, period long enough to have thoroughly saturated them with water.
 With this general result as basis, Messrs. Macdonald and Mead con tinued their experiments until they proved conclusively that while the rocks that have been sliding contain the high percentage of water men, tioned, this water is largely in capil- lary form and cannot be effectively drained except to the extent of pos sibly 4 or 5 per cent by any system that could be devised. No more con- vincing argument can be advanced to prove that not deep drainage of the weak rocks but vigorous digging away by dredges of the material now sliding, Is the remedy for the slides under present conditions.
 One Theory Absurd.
 A theory held tenaciously during the dry excavation construction period among the engineers directly connect ed with the Culebra cut was that the high ground above the canal channel should be allowed to slide so as to reduce the amount of blasting. This was one of the many ideas that Gen eral Goethals had to overrule during the building of the canal. These ex- periments prove that he was abso- lutely correct from a scientific geolog- ical viewpoint in overruling this the ory and in digging away with steam shovels as much earth as possible of the banks that might slide Geologist Macdonald from the first maintained that initial movement and by this the great weakening of the canal banks should be prevented by terracing the slopes back with steam shovels; for before any movement occurred, slopes might be maintained at an angle of something like one in three, or steep CT; but after movement was once started, tse sheared rocks could con- tain enough extra ground water to bring them almost to the consistency of mud. They would, therefore, stand only at very flat angle, perhaps at one in ten.
 prove that this is what actually has been happening. They prove that the rock in the canal banks that has given the recent trouble Is not weakened or affected to any special degree by heavy rains except after is has moved and thus been weakened
 Geologist Vindicated.
 Tn uio Af will be interested to know that Mir. MacDonald's officially printed reports as long as five years ago emphatically urged upon the division engineer then in charge of the excavation of the Culebra club that these banks that have recently caused trouble by slid ing be dug back until the slopes were very much fatter than they were when | these recent slides occurred, just | where Macdonald predicted they l might be expected.
 | The division engineer of the central division, of which the Culebra cut was the principal part, was always | absolutely convinced that the slopes | considered safe by engineering prece- dents rather than those the canal | geologist recommended and urged would be the ones at which to stop steam shovel excavation. This engi- neers opinion influenced General Goe- thals. until the time came, as 1t did, when the general found that he had to take personal charge of the exca- vation work in the Culebra cut. When | 1 came to see more in detail the recon.