TOOLS—Three or four good axes, several bill-hooks, a good hatchet with hammer head and nail-puller should be in the tool kit. In addition, each man should be provided with a belt knife and a machete with sheath. Collins makes the best machetes. His axes, too, are excellent. The bill-hook, called foice in Brazil, is a most valuable tool for clearing away small trees, vines, and under-growths. It is marvellous how quickly an experienced hand can clear the ground in a forest with one of these instruments. All of these tools should have handles of second-growth American hickory of first quality; and several extra handles should be taken along. The list of tools should be completed with a small outfit of pliers, tweezers, files, etc.—the character, of course, depending upon the mechanical ability of the traveller and the scientific instruments he has with him that might need repairs.

SURVEY INSTRUMENTS—The choice of instruments will depend largely upon the character of the work intended. If a compass survey will suffice, there is nothing better than the cavalry sketching board used in the United States Army for reconnaissance. With a careful hand it approaches the high degree of perfection attained by the plane-table method. It is particularly adapted for river survey and, after one gets accustomed to its use, it is very simple. If the prismatic compass is preferred, nothing smaller than two and one half inches in diameter should be used. In the smaller sizes the magnet is not powerful enough to move the dial quickly or accurately.

Several good pocket compasses must be provided. They should all have good-sized needles with the north end well marked and degrees engraved in metal. If the floating dial is preferred it should be of aluminum and nothing smaller than two and one half inches, for the same reason as mentioned above regarding the prismatic compass.

Expense should not be spared if it is necessary to secure good compasses. Avoid paper dials and leather cases which absorb moisture. The compass case should allow taking apart for cleaning and drying.

The regular chronometer movement, because of its delicacy, is out of the question for rough land or water travel. We had with us a small- sized half-chronometer movement recently brought out by the Waltham Company as a yacht chronometer. It gave a surprisingly even rate under the most adverse conditions. I was sorry to lose it in the rapids of the Papagaio when our canoes went down.

The watches should be waterproof with strong cases, and several should be taken. It would be well to have a dozen cheap but good watches and the same number of compasses for use around camp and for gifts or trade along the line of travel. Money is of no value after one leaves the settlements. I was surprised to find that many of the rubber hunters were not provided with compasses, and I listened to an American who told of having been lost in the depths of the great forest where for days he lived on monkey meat secured with his rifle until he found his way to the river. He had no compass and could not get one. I was sorry I had none to give; I had lost mine in the rapids.

For the determination of latitude and longitude there is nothing better than a small four or five inch theodolite not over fifteen pounds in weight. It should have a good prism eyepiece with an angle tube attached so it would not be necessary to break one's neck in reading high altitudes. For days we travelled in the direction the sun was going, with altitudes varying from 88° to 90°. Because of these high altitudes of the sun the sextant with artificial horizon could not be used unless one depended upon star observations altogether, an uncertain dependence because of the many cloudy nights.

BAROMETERS—The Goldsmith form of direct-reading aneroid is the most accurate portable instrument and, of course, should be compared with a standard mercurial at the last weather-bureau station.

THERMOMETERS—A swing thermometer, with wet and dry bulbs for determination of the amount of moisture in the air, and the maximum and minimum thermometer of the signal-service or weather-bureau type should be provided, with a case to protect them from injury.

A tape measure with metric scale of measurements on one side and feet and inches on the other is most important. Two small, light waterproof cases could be constructed and packed with scientific instruments, data, and spare clothing and yet not exceed the weight limit of flotation. In transit by pack-train these two cases would form but one mule load.

PHOTOGRAPHIC—From the experience gained in several fields of exploration it seems to me that the voyager should limit himself to one small-sized camera, which he can always have with him, and then carry a duplicate of it, soldered in tin, in the baggage. The duplicate need not be equipped with as expensive a lens and shutter as the camera carried for work; 31/4 x 41/4 is a good size. Nothing larger than 3 1/4 x 5 1/2 is advised. We carried the 3A special Kodak and found it a light, strong, and effective instrument. It seems to me that the ideal form of instrument would be one with a front board large enough to contain an adapter fitted for three lenses. For the 3 1/4 x 4 1/4:

One lens 4 or 4 1/2 focus

One lens 6 or 7 focus

One lens telephoto or telecentric 9 to 12 focus

The camera should be made of metal and fitted with focal-plane shutter and direct view-finder.

A sole leather case with shoulder-strap should contain the camera and lenses, with an extra roll of films, all within instant reach, so that a lens could be changed without any loss of time.

Plates, of course, are the best, but their weight and frailty, with difficulty of handling, rule them out of the question. The roll film is the best, as the film pack sticks together and the stubs pull off in the moist, hot climate. The films should be purchased in rolls of six exposures, each roll in a tin, the cover sealed with surgical tape. Twelve of these tubes should be soldered in a tin box. In places where the air is charged with moisture a roll of films should not be left in a camera over twenty-four hours.

Tank development is best for the field. The tanks provided for developing by the Kodak Company are best for fixing also. A nest of tanks would be a convenience; one tank should be kept separate for the fixing-bath. As suggested in the Kodak circular, for tropical development a large-size tank can be used for holding the freezing mixture of hypo. This same tank would become the fixing tank after development. In the rainy season it is a difficult matter to dry films. Development in the field, with washing water at 80 degrees F., is a patience-trying operation. It has occurred to me that a small air-pump with a supply of chloride of calcium in small tubes might solve the problem of preserving films in the tropics. The air-pump and supply of chloride of calcium would not be as heavy or bulky as the tanks and powders needed for development. By means of the air-pump the films could be sealed in tin tubes free from moisture and kept thus until arrival at home or at a city where the air was fairly dry and cold water for washing could be had.

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