New England State, and two of them are as large as Virginia and
Ohio, and nearly as large as New York and Pennsylvania. Luzon and
Mindanao," and the professor pointed to them on the map, "the most
northerly and the most southerly, have each about 40,000 square miles,
and the area of all the islands is 116,000 miles. I think most of you
could have no idea from your study of maps of the extent of the
Philippines.

"Mindoro, the next island south of Luzon, has 9,000; and the others from
1,200 to 5,500. I shall not mention or describe them separately. We
shall visit only Manila and the country near it, and you would not
remember even the names of the islands over night. They are all
mountainous and volcanic. The highest mountain is Apo, in Mindanao,
which is 10,400 feet high, and there are others of 9,000 feet.

"The islands are volcanic, and therefore subject to earthquakes; and an
instrument in Manila which indicates vibrations of the earth is said to
be shaking about all the time. Several destructive ones are recorded in
the past. In 1863 Manila was nearly destroyed by one, and the great
southern island is especially liable to them.

"The mountain ranges mostly extend north and south; and there is space
between them for some considerable rivers, as the Rio Grande in Luzon
has a course of 220 miles. The Agusan in Mindanao is navigable for 60
miles. In this island are several lakes, with rivers flowing from them.
In addition to which are many lacustrine basins."

"Spare us, Professor!" exclaimed Uncle Moses.

"The word comes from _lacus_, Latin for lake, and applies here to such
lakes as send their overflow to the sea or other lakes by streams made
by the rush of water. But I don't use many such words, and I hardly
expected a classical scholar to object," replied the professor.

"But I objected in behalf of several here who never studied Latin; and
besides the overflow is entirely apart from the root of the word. But I
am satisfied, and the commander may invite you to proceed," chuckled
Brother Avoirdupois.

"On account of the high mountains and the abundant sea-breezes, though
hot and moist, this group is not so unhealthy as most tropical islands
and countries. The fevers of hot countries are here of the mild,
intermittent kind"--

"What is intermittent, Professor?" asked Felix. "Is it the kind they
don't have in Ireland?"

"I should say that it was."

"An intermittent fever, Felix, is one that comes and goes