��Popular Science Monihly
��ease as if the vessel were tied to a wharf. Many thousands of barrels of oil are thus shipped from Tuxpan each year. The success of the first lines at Tuxpan stimulated the installation of many others at, or near the port, until the submarine method of loading oil has become standard in the region. The method by which the pipe lines are laid is no less interesting than their function.
How the Pipe
Line Is Laid A trench is first dug through the sand dunes near the beach, until a smooth, even grade is secured down to tidewater. On this grade short ties are laid back from the beach. On these ties light rails are laid, the gage being less than afoot. On this narrow railway small carsor"dollies" ride. The pipe sections arc connected on shore beside this narrow- gage track, lifted upon the "dollies," and thus trans])or- ted into the ocean. A steamshij) on the bar plays the part motive to the dollies, emi)loyed.
As a rule the lines are made ti|) of 8-inch steel [)i[)eand api>roximale a mile and a half in length. l'"re(|nently a small hoisting-engine has to be installed alcmg
the track to aid the steamship at sea in pulling the line. By fastening a cable back of a coupling on the line and run- ning it over one of the drums on the hoisting engine, substantial aid can be gi\'cn in this work of hauling.
���The fog-stick is run out from the steamer on a steel towHne by means of a pulley
��the other side of of hauling loco- a hauser being
��A Fog- Stick Guide for Traffic on
the Great Lakes N very foggy weather the barges towed by steamers on the Great Lakes are often lost to sight, so that the safety of both steamer and barge is jeopardized. The fog-stick shown in the accompan\'ing illustration was designed to meet this condition. It is sent f)Ut from the steamer on the steel towline
by means of a pulley or block, and is run up close enough to the barge to be always visi- ble to the man at the forward wheel and to indicate the direction in which the tow- line is leading and conse- quently the relative po- sition of the steamer.
Rope guys hold the fog- stick at the retjuired dis- tance from the bow of the boat and a weight composed of a bag of sand keeps it up- right. At night, or w h e n e v e r the fog is (hick enough to war- r a n t it, a lantern is suspended from the pole.
Why the Color of Sea Water Is Blue or Green ^IIV is the ocean blue? Because of the rellection of the sky? This accoimts for some of the color but it is largely a matter of saltness and density. In the tropics where the inten.se hea^ and rapid e\aporation cause the water to be much saltier the blue is vivid, while the further one goes toward the poles the greener the hue becomes until it is almost as \i\id as the tropical azures.