This was the background of our labors, our la_bor_atory as our English visitors called it: cool in the daytime, cold at night, where one could work as well as in the north, and where a morning's tramp usually furnished material sufficient for a week of research. We came to know it as the house of a thousand noises. The partitions, like those of all tropical houses, extended only part way to the ceiling, so, as some one has said, one enjoyed about the privacy of a goldfish. It would have been a terrible place for a victim of insomnia; but when we were kept awake by noises it was because we were interested in them. After a day's hard work in the jungle, it must indeed be a bad conscience or a serious physical ailment which keeps one awake a minute after one rolls up in his blanket. Through all the months of varying tropical seasons we slept as soundly as we should at home. I can do with five or six hours' sleep the year round, and I begrudged even this in the tropical wonderland, where my utmost efforts seemed to result in such slight inroads into our tremendous zoölogical ignorance. At night I spent many wonderful hours, leaning first out of one, then out of another window, or occasionally going down the outside lattice stairway and strolling about the compound. No two nights were alike, although almost all were peaceful, with hardly a breath of air stirring--just the cool, velvet touch of the tropics, always free from any trace of the heat of the day. Whether dark rich olive under crescent or starlight, or glowing silvery-gray in the flood of the full moon, the forest, so quiet, so motionless all about me, was always mysterious, always alluring. To the north, at the foot of the hill, lay the dark surface of the great river, its waters one amber, homogeneous flood, yet drawn from a thousand tributaries: hidden creeks seeping through mossy jungles far beyond the Spanish border, brown cascades filtering through gravel which gleamed with yellow gold and sparkled with the light from uncut diamonds. And to the south rose the wall of the jungle itself, symbol of all that is wild and untamed in nature.