32. TRANSACTIONS OF THE [ocr. 2%, 
persons to occur near the pebble beach of Pescadero, and parti- 
culars were communicated to us in 1885 by Mr. J. W. Redway, 
so I did not personally examine this region. 
6. San Francisco. Extensive sand-dunes form a conspicuous 
feature in the ocean suburbs of San Francisco. Powerful winds 
from the broad Pacific drive the sand city-ward and formerly 
threatened to submerge ashifting real estate—a region of ‘‘ sand- 
lots,” world-notorious through the pseudo-oratory of a mischiev- 
ous demagogue. 
Recently scientific arboriculture has reclaimed a large tract 
for the Golden Gate Park. Extensive dunes still remain, some 
of them measuring 50 to 60 feet on their steepest incline; on 
the lee side the sand lies at the angle of rest, which here is 31°, 
the same as in Evypt, Bermuda, and the Hawaiian Islands. In 
the dry season the sand is quite mobile, but, notwithstanding 
these favorable conditions, it is utterly devoid of sonorous prop- 
erties, owing to its shaly and siltose constitution. The beach 
sand south of the Cliff House is also non-sonorous for the same 
reason, 
%. Laguna Beach. 'This beach lies on the ocean about five 
miles north of Golden Gate, and was reached via Saucelito, The 
sand here, too, is shaly and wholly non-sonorous. Reporting the 
occurrence of non-musical sand may be uninteresting, but is not 
altogether superfluous, for negatives are of importance in estab- 
lishing affirmatives, 
8. Mexico. Mr. W. Waddell, nowin Brazil, but a resident of 
Mexico for fifteen years, has furnished me with data of a sonorous 
sand-hill in the Peninsula of Lower California. A gentleman of 
accurate thought and a close observer of nature, he responded 
to my pertinacious questioning in so satisfactory a manner as to 
leave no doubt concerning the nature of the phenomenon and 
the character of the locality. 
In the year 1885, just before the close of the dry season, Mr. 
Waddell was with a party of Mexicans on a schooner fitted out 
for the capture of turtles. They coasted along the Pacific shore 
of Lower California and made landings at many points. About 
60 miles north of Cape San Lucas, the extreme southern end of 
the Peninsula, the party landed, and one of them climbed to the 
top of a dune to get a view of the neighborhood—in short, to 
prospect for turtles—and observed a sound issuing from the dry 
loose sand disturbed by his act. Mr. Waddell, standing near, also 
heard the sound, and, having previously read of the Mountain of 
the Bell, at once recognized the phenomenon. This dune is 
about 70 feet high (memory-measure), and shaped like the half 
of a lens ; its sides are covered in part with plants common to 
