It is somewhere between December 1906 and January 1907.  Nine year-old Charles Breasted is traveling with his parents on the Nile River from the Fourth Cataract northward toward the Third Cataract, i.e. near Dongola in present-day Sudan.  His father, the noted Near Eastern archaeologist James Henry Breasted, is exploring the area in search of ancient inscriptions and forgotten archaeological sites.

From Pioneer to the Past, by Charles Breasted, pages 193-194:

“As we drew nearer the Cataract every bend and headland revealed enchanting hidden backwaters with little crescent beaches fringed with thorn and castor bushes, and overhung by palms, acacias and tamarisks.  Occasionally, like those in the Fourth Cataract, such places sheltered little patches of soil cultivated by a few Nubians, living in wattle huts, who stared at us as we drifted past.  Except for the fact that probably none of them had ever beheld a white child before, they were never surprised to see us: for by that mysterious way in which a native in Khartoum would know of a happening in Cairo before the European had learned it from his clicking telegraph, these remote, isolated people had for days been informed our whereabouts and almost hourly progress.

We never ceased marveling at their ability to converse with one another across great stretches of water.  Again and again in places where the Nile had suddenly widened to a breadth of almost two miles, so that we would have to inquire locally regarding possible inscriptions or ruins along the farther shore, we would watch a man address a friend so far away on the opposite bank as to be a mere speck wholly out of earshot.  He would stand at the very edges of the river perhaps ten feet above its surface, and cupping his hands some four inches in front of his lips, would talk into the water at an angle of about 45º, in a loud voice but without shouting.  At intervals he would stop to listen while the distant man evidently replied in kind.  But we who stood close by heard no sound.  Presently the exchange would end, and he would tell us in a matter-of-fact way what he had learned.”

When I read this I thought it was a fascinating example of pre-industrial, pre-modern people with an unexpected grasp of the properties of the natural world.  Remember the Harry Potter books and Mr. Weasley’s fascination with non-magic technology?  He collected televisions, telephones, automobiles and other technological inventions.  He was fascinated to learn how it is that muggles, people with no magical abilities, manage to do things that wizards take for granted.  Here we have an example of “magic” in real life.  How did people in the past spread news over long distances?  How is it that the messenger sent out on a fast horse or ship from a big Roman battle would almost without exception arrive after the rumor of the events had reached Rome?  In Book VII, part 3 of Caesar’s “Gallic Wars” he writes,

“The report is quickly spread among all the states of Gaul; for, whenever a more important and remarkable event takes place, they transmit the intelligence through their lands and districts by a shout; the others take it up in succession, and pass it to their neighbors, as happened on this occasion; for the things which were done at Genabum at sunrise were heard in the territories of the Arverni before the end of the first watch, which is an extent of more than a hundred and sixty miles.”

But perhaps, like the Nile River tribes, “shouting” was a more direct and long-distance mode of communication than we think possible in our modern world.  Perhaps there are some places and times with acoustics that don’t even require shouting for a call to travel over long distances.  Would the ancients have mastered something like that?  The evidence of these “primitive” tribes living along the Nile in the early 1900’s suggests that they certainly could have.  My husband grew up on a farm in Iowa.  He recalls that on some cloudy days the sound from farms a few miles away would travel such that he could hear people who were outside speaking in normal tones.  The people along the Nile must have experimented with ways to get the sound waves to bounce along the top of the flowing river just like rocks skipping across the water so that the friend on the other side could catch them.  Today the skill is probably lost.  Who needs it when you can pick up your cell phone and call the guy in the next village?  The cell phone is a superior device, but we shouldn’t take for granted that our ancestors didn’t invent their own kinds of “magic.”