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 78 THE CONDOR VoL. XI on the south face. There are of course, as in other quarries, a few crevices and cracks in the face due to water and to the blasting, and it was in these cracks in the solid rock that the swifts selected sites for their homes. During the past eighteen years I have been a frequent visitor to all parts of the mountain, but it was in the summer of 1904 that I first noticed the swifts. In 1905, 1906, and 1907, I occasionally noticed them flying above the mountain, some- times hundreds of them. In December, 1907, while inspecting the old quarry on the top of the hill I decided that the south face would prove to be interesting to an ornithologist and from that time my hours of leisure .on Sundays were spent in the quarry. Some days I would find the birds circling about the top of the mountain, making an occasional swoop with bullet-like speed thru the gulch, where their peculiar harsh notes were re-echoed and re-inforced by the rock walls, thus making one expect to see birds much larger than the swifts. Sometimes these rapid swoops would end in the cracks, about ten feet from the floor, in the south face. I say in the cracks instead of at the cracks, for their aim almost always was so true that the two-inch opening did not seem to cause them to slow up. Some of my visits were not so pleasing to me, for upon several occasions I could find no signs of the birds,' while upon other trips I could hear the birds "in the rocks" but could not make them come out. When April, 1908, came around I was convinced that I was observing the correct place; but I did not see any possibility of securing eggs or of even seeing them, for the seams they favored were either so crooked or extended so far that nothing could be seen no matter where the rope was lowered. During April, I was called to the East, so told the quarryman, Mr. J. J. Matthews, about the birds and asked him to keep his eyes on them when on that part of the hill, because he might be rewarded by finding a nest. Mr. Matthews became very much interested in the quest and as he was an expert in rope climbing a more desirable assistant could not be hoped for. When I returned early in May, Mr. Matthews informed me that he had found a nest of "those rare birds" and better yet that the nest could be seen from the crack in the .rock, and best of all that he thought that we would be able to secure the nest by some hard work. This was encouraging news, and armed with permits from the California Portland Cement Co., and the State Board of Fish Commissioners, we made plans to observe the nest regularly and secure some eggs if possible. A walk to the top of old Slover and a rope climb proved to be good exercise, after working hours. The fact that there was so much work connected with the observations made me admire the White-throated Swifts even more than I had before. Nest no. 1 was reached by throwing a rope from the top of the quarry to the ground and then climbing up the rope from the bottom and working along the face by means of friendly crevices. If the rope had been lowered directly above the nest we would have been several feet from the face and could not have workt to advantage. The nest was about eighteen feet from the floor of the quarry and forty from the top, and was situated in a crevice from one to three inches in width, about four feet long and extending back about two feet. The nest was only about one foot from the face and was firmly glued between the two walls, probably by means of saliva, but some of the weight may have been supported by a few projec- tions from the rocks. Judging from the rate at which nest no. 1 progrest after we first saw it, we think it was started about April 15. It seemed to be almost done on May 1, but it continued to be improved upon day by day and on May 16 we observed the first egg. More improvements were made during the next few days and on May 19 there were two eggs, and on May 22 another. During most of these observations