parts of George’s artificial horizon
Fig. 1 is the instrument complete. A, the mercurial reservoir; B, the observing trough; C, the stop-cock; D, the cylindrical stop.
Fig. 2 is the instrument with the parts of the observing trough removed, which are shown above it. E, rim with glass shade; F, rim without glass shade; G, the glass that floats on the surface of the mercury.
Fig. 3. Position of the instrument while filling the observing trough.
Fig. 4. Position of the instrument while returning the mercury into its reservoir.
In moderate weather the glass G will be quite sufficient protection against the wind, but in gusty weather screw on the rim F, but it must not touch the glass G.
The glass E will protect it from any weather, taking care to level the ground on which the horizon stands.
In filling the observing trough, be careful that the glass cover, E, is screwed on tight; by pressing on the cylindrical stop D (Fig. 1) the mercury flows quickly: the trough half filled, as shown in Fig. 3, is sufficient for ordinary observations; but for very low altitudes the trough must be three-quarters filled or more as found necessary to raise glass G (Fig. 1).
use of George’s artificial horizon
Before returning the mercury into the reservoir, unscrew the short tube near the stop-cock, tapping it smartly at the same time, to shake down the globules of mercury that may remain in the tube; there is a small hole in the screw, which must be brought in sight, then turn the stop-cock, and the mercury will run rapidly into the reservoir. When about to use a sextant and artificial horizon of the common form of construction, our first care is to select a tolerably level, and, if there be wind, a sheltered spot of ground, with a clear view to the north or south, or, if the stars admit of a north and south observation, to see that the view is clear both ways. On this we place our artificial horizon, sometimes on our sextant case, sometimes on a stand (wash leather), but seldom, if we can avoid it, on the bare ground, because then the mercury, if spilled, would be difficult to gather up. The horizon roof we keep near to cover the mercury, in case wind should arise, but we never use it unless in case of necessity; then, sitting either north or south of the horizon, according to the position of the celestial object, we look with the naked eye for its reflected image in the mercury, and so seat ourselves that we can conveniently keep it steadily in view. We set the sextant nearly to zero, and look up without the telescope to the sun or star, and then, gradually moving the index forward, we bring its image down to meet the reflection in the quicksilver; then, screwing on the inverting telescope, which is the simplest and best for observation, we move the index by hand, till the contact is nearly perfect; then fasten the index by the clamping screw, and with the tangent screw complete the contact; and so long as the object is rising, by gradually turning the tangent screw we keep the images together; when they separate more slowly, and at length remain in contact for nearly half a minute, we know that the meridian altitude has been observed; we wait another minute to see them separate in the opposite direction as the body begins to descend, and then read off the observed altitude. Our illustration will sufficiently explain that the sextant is held in the left hand and the tangent screw worked with the thumb and forefinger of the right. Fig. 2 is the method recommended by Captain George: the arc is steadied by the forefinger, and the tangent screw turned by the middle finger and the thumb; a police or bull’s-eye lantern is good to read off by, and the light, of whatever nature, should be placed behind the observer, so that it may not interfere with his work, and yet may be ready for him to use when he wishes to read his altitude.
The following directions for the projections of routes by Captain George, R.N., are so thoroughly plain and practical that it will be well for the travelling observer to have recourse to them:—For out-door or field work the easiest method is by the plane projection, the data thus obtained being transferred to a Mercator’s projection at the first halt or stopping station. In the plane projection one equal length is assigned to all the degrees of latitude and longitude. It was first adopted on the erroneous supposition that the earth’s surface is a plane; it is still the best for the traveller to use in his early attempts to project his journey while the objects are still in sight. This projection is available as far as 20° on either side of the Equator; beyond the parallel of 20° and as far as 60° Mercator’s projection is preferable. Between 60° and the pole the distortion of both the plane and Mercator’s projection is so apparent, that a polar or circular projection must be adopted. Sheets of paper, ruled into squares by strong lines, and subdivided by finer ones, afford great assistance in map work. Forout-door work the scale of 1in. to one mile is amply large enough to register every particular of one day’s journey on a sheet of 12in. square. The in-door, or table plan, may be reduced ten miles to the inch, and plans for transmission home maybe again reduced to 1in. to 1° when larger plans cannot be sent. The chief point aimed at in the following directions is to draw more attention than has hitherto been given to the true bearing of objects, for the following reasons: First. Any object whose true bearing is east or west must be in the same latitude as the place of the observer. Secondly. Any object whose true bearing is north or south must be in the same longitude as the place of the observer.
computing projection of routes
While travelling in a northerly or southerly direction, from a station whose latitude is known, and carefully noting the distance and direction travelled, it is only necessary to watch when objects come to the true east or west, and their latitude is obtained. When travelling in an easterly or westerly direction from a fixed station, noting distance and direction, it is only necessary to watch when objects come to the true north or south, and their difference of longitude can be obtained by using Table B, from the station left. Thus, suppose a traveller passes from A, whose latitude is known, towards some distant hill (B), his route making an angle of 25° with the meridian. He sets his sextant to 65° (65° + 25° = 90°), or to 115° (180° - 65°); then as the objects 1, 2, 3, and 4 successively come into contact with B or A, as the case may be, he ascertains with precisionthe moment when they are truly east or west of him, and so, knowing the distance he has travelled from A, he can readily calculate or project their latitude.
When the traveller, as will frequently be the case, has to deviate from the line of route, his position can be determined by compass, or true bearing of any object, and an angle of a second object; or he may have recourse to transit observations; that is to say, wherever two fixed objects come in line, an angle to a third object will determine the position with great accuracy.
computing deviation from route
Observe that in travelling along X Y Z the hills A B C can be mapped for at X, or thereabouts; the bearing of B from C can be determined at Y; that of A from B; and at Z that of A from C, and so on, for any number of hills. And it is very important to recollect that it is not necessary to catch these lines of sight precisely, for by taking bearings twice, and the intermediate course approximately, there are sufficient data for protracting out upon paper the required bearing.
Thus, as soon as the peak of a distant hill is about to be occulted by the shoulder of a nearer one, a bearing should be taken, and again another as soon as it has reappeared on the other side, and the intermediate course noted.
The advantage of this method of filling up a field sketch will become more apparent as experience is gained. A third and accurate method of fixing the position is in general use among marine surveyors, but has hitherto been but little resorted to by land travellers, viz., by the angles subtended between three known objects. The instrument called the station-pointer is generally used for this purpose, but the position may also be found with a pair of compasses and a protractor,or more simply as follows by means of a protractor and a sheet of tracing paper. Draw a line through the centre of the paper, place the protractor on it, near to the bottom of the sheet, lay off the right hand angle to the right, and the left hand angle to the left of the centre line; rule pencil lines, radiating from the point over which the centre of the protractor had been placed, to the points that had been laid off, then place the paper on the plan or map, and move it about until the three lines coincide with the objects taken, prick through the points that lay beneath the centre of the protractor, and the observer’s position is transferred to the plan. When possible the centre object should be the nearest.
On a sheet of cartridge paper, 38in. by 20in., it is proposed to construct a map on Mercator’s projection, on a scale of ten miles to an inch equatorial,i.e.6in. to a degree of longitude.
Draw a base line, find its centre, and erect a perpendicular to the top of the paper; the extremes of longitude 34° and 36°, added together and divided by 2°, give 35°, the central meridian, and which is represented by the perpendicular. On each side of it lay off 6in., and erect perpendiculars for the meridians 34° and 36°; divide the base line into ten mile divisions, and the part from 35° 50´ to 36° into miles for the latitude scale. From Table A take the following quantities:—
Having thus obtained the distance between the required parallels, divide the map into squares of ten miles each way, and the map is ready for the projection of the route.
A.—Table to construct Maps on Mercator’s Projection.
Use of the table.—Find the required parallel; the tens at the side, and the units at the top. At their intersection will be found in degrees and minutes the distance of the required parallel from the next less degree, to be measured from the scale of longitude on the map in progress.
Given the parallel of 30°, required that of 31°. 30 at the side and 1 at the top intersects at 1° 09·6´, the required distance of the two parallels.Given the parallel of 31°, required that of 33°:°°´32 =110·433 =111·1221·5the distance between the 31° and 33° parallels.
Given the parallel of 30°, required that of 31°. 30 at the side and 1 at the top intersects at 1° 09·6´, the required distance of the two parallels.
Given the parallel of 31°, required that of 33°:
B.—Given the Departure to find Difference of Longitude.
Use of the table.—Find the required parallel, the tens at the side and the units at the top, at their intersection will be found a quantity, which, multiplied by the departure, gives the difference of longitude.
The departure from the meridian on the parallel of 34° was 25 miles, required the difference of longitude:25´ × 1·20 = 30·00´ the difference of longitude.In the parallel of 60° the departure was 30 miles:30´ × 2 = 60 miles, or 1 degree.In the parallel of 35° N. the route was N. 40° W. 37 miles distance.By traverse table, 40° course, dist. 37° = dep. 23·8´ × 1·22 = 29·03 miles difference of longitude.
The departure from the meridian on the parallel of 34° was 25 miles, required the difference of longitude:
25´ × 1·20 = 30·00´ the difference of longitude.
In the parallel of 60° the departure was 30 miles:
30´ × 2 = 60 miles, or 1 degree.
In the parallel of 35° N. the route was N. 40° W. 37 miles distance.
By traverse table, 40° course, dist. 37° = dep. 23·8´ × 1·22 = 29·03 miles difference of longitude.
The following example will serve to show how the traveller’s record of progress may be conveniently kept. It was framed by S. W. Norie expressly for the use of navigators; but explorers and travellers will find it a simple and useful form for recording the day’s work:
The difference of latitude 118·8 and departure 109·0 give the course N. 42° 32´ E., and distance 161·2.
The difference of latitude 118·8 and departure 109·0 give the course N. 42° 32´ E., and distance 161·2.
In traversing regions watered by rivers and running streams, it not unfrequently becomes important to ascertain the speed at which they flow in their downward course towards the sea, and the following directions given by Captain George, R.N., are so perfectly clear and practical that both time and trouble will be saved by the traveller who follows them out in conducting his investigations. The data required are—the area of the river, section, and the average velocity of the whole current. All that a traveller is likely to obtain without special equipment is the area of the river, section, and the average velocity of the “surface” of the current which differs from that of its entire body, owing to fractional retardation at the bottom.
To make the necessary measurements, choose a piece where the river runs steadily in a straight and deep channel and where a boat can be had. Prepare half a dozen floats of dry bushes, with paper flags, and be assured they will act. Post an assistant on the river bank at a measured distance (of about 100 yards), down stream, in face of a well-marked object; row across stream, in a straight line, keeping two objects on a line in order to maintain your course. Sound at regular intervals from shore to shore, fixing your position on each occasion by a sextant angle between your starting place and your assistant’s station, and throw the floats overboard, signalling to your assistant when you do so, that he may note the interval that elapses before they severally arrive opposite him. Take an angle from the opposite shore to give the breadth of the river. To make the calculation approximately, protract the section of the river on a paper, ruled to scale in square feet, and count the number of squares in the area of the section. Multiply this by the number of feet between you and the assistant, and divide by the number of seconds that the floats occupied on an average in reaching him.
Important rivers should always be measured above and below their confluence, for it settles the question of their relative sizes, and throws great light on the rainfall over their respective basins. The sectional area at the time of the highest water, as shown by marks on the banks and the slope of the bed, ought also to be ascertained.
Many highly-accomplished travellers fail to obtain much reliable information beyond the actual limit of their own observation, because they do not sufficiently allow for the great difference in the manner of expressing a geographical idea between an educated European observer and an untutored savage; and yet it would not be too much to say that the latter has often enough a thoroughly practical idea of the district he actually knows.
The man who wants information must not talk latitude and longitude to a native or to an uneducated European, nor must he expect them to shape their answers to the form in which he expects to receive them; for if he does he may be told that “rivers run from the sea to the mountains,” and other absurdities, which are related as proofs of native stupidity, when they are in reality no more than discrepancies between the form of question and that of the answer. At the same time he must estimate the mental calibre of his informant, and avoid wearying him too much; for sometimes the native mind, over burdened with a succession of ideas, becomes confused, and not unfrequently suspicious, and in this last case actual falsehoods will be told, in order to gain time to find out the intention of the questioner, before the truth is revealed.
In all dealings with natives the European must remember that they have no idea of the value we place upon time; there is no use in saying, “Let us come to the point at once.” It is far better, indeed it is absolutely necessary, to delay judiciously, as there is always an implied contest between visitors; and the man who is in a hurry to speak loses dignity. Do not disturb your informant’s train of thought, but try to accommodate your own to it. Let him tell as minutely and tediously as he pleases how he has travelled; how long he walked with the rising sun on his right or left; how much he turned either way; where he halted for rest or refreshment; whether he crossed rivers on foot or in canoes; induce him, if possible, to trace a map upon the ground, in doing which he will most probably begin by making the direction of all his lines coincide with the actual bearing of the country; for natives, though they may be brought to comprehend a map when its north point coincides with the real north, cannot believe that it is also right when it is placed in any other position. We have frequently tested Hottentots with regard to the direction of places a thousand miles distant, and have found them point as correctly as we could take the bearing with a pocket compass.
Sometimes it will be found that the same individual will give a river a dozen different names; and this is often because, in speaking of the different parts of it, he gives to each the name of the chief who has his village there, and who “drinks water” at the place which is called after him; therefore, endeavour to ascertain whether the river has a real name, and do not apply to it the first and, perhaps, the most inappropriate name that is given.
Europeans who have settled in the colonies, and have become traders or hunters, frequently push very far into the interior, and such men have generally very clear ideas of direction and locality, but are often very modest and diffident when asked to furnish information to be laid down on paper. In 1849, while staying at the Vaal River, we persuaded our friend Macabe, with some difficulty, to give us the length in “hours” and the direction of the various stages of his journey on the river Limpopo. These, with the rivers, mountains, villages, and other features of the country, we laid down, on a scale of one inch to a mile, on several sheets of cartridge paper, and tested the correctness of our work by laying it on the floor, with its north coinciding with the real north, and requesting our Dutch visitors to stand as if they were about commencing the same journey, and indicate how much they turned to the right or left as they proceeded.
The following facts relating to time should be impressed on the memory of every traveller:—The earth is divided in its circumference into 360°; the day is divided into twenty-four hours. It therefore follows that 15° of longitude will represent one hour of time; consequently, as you travel towards the east, when you have journeyed over 15°, you will have gained one hour on the sun, which will rise just one hour earlier than it did at the starting point.
If natives accompany you on a journey, ask them to point in the direction of places at different times, and particularly to tell you whenyou are exactly abreast of them, as well as before, and after you have passed, and thus, by a kind of rough triangulation, you will gain their approximate position.
If cattle stray to great distances, ask the men who go after them the reason of their having taken any particular direction, and you will probably gain some information respecting the form of valleys or mountains, and perhaps of watering places.
In North Australia we were led by the tracks of horses, which had been lost about a fortnight, to a considerable stream.
By the courtesy of Mr. H. W. Bates, F.R.C.S. and Asst. Sec. R.G.S., we are enabled to furnish our readers with the following valuable and practical information regarding the gathering together and preserving such objects of natural history as he may be fortunate enough to discover:—
Travellers (says Mr. Bates) who intend devoting themselves especially to natural history will generally possess all the requisite information beforehand. It is to those whose objects or duties are of another nature, or who, whilst on a purely geographical land expedition, wish to know the readiest means of collecting, preserving, and safely transmitting specimens they collect, that the following hints are addressed.
Outfit.
Double barrel guns with spare nipples, and a few common guns to lend to native hunters, especially if going to the interior of tropical America. Fine powder in canisters, and fine shot (Nos. 8 and 11), must be taken from England; coarse powder and shot can be had in any part; a good supply of the best caps. Arsenical soap, a few pounds in tin cases; brushes of different sizes; two or three scalpels; scissors (including a pair of short bladed ones); forceps of different sizes for inserting cotton into the necks of birds’ skins; needles and thread. A few small traps with which to capture small (mostly nocturnal) animals; strong landing net for water mollusks, &c.; two stout insect sweeping nets; cylindrical tin box, with shoulder strap, for collecting plants; a few dozen of small and strong broad-mouthed bottles, and a couple of corked pocket boxes; insect pins, a few ounces each of Nos. 5, 14, and 11; stone jars, for reptiles and fishes in spirit, to fit four in a box, with wooden partitions. If animals in spirit are to be collected largely, a supply of sheet tin, orzinc, with a pair of soldering irons, and a supply of soft solder, must be taken instead of stone jars: cylindrical cases can be then made of any size required. By means of the soldering apparatus also empty powder canisters or other tin vessels can be easily converted into receptacles for specimens; a ream or two of botanical drying paper, with boards of same size as the sheet, and leather straps; a few gross of chip pill boxes in nests; a dozen corked store boxes (about 14in. by 11in. and 2½in. deep) fitted perpendicularly in a tin chest; a few yards of indiarubber waterproof sheeting, as temporary covering to collections in wet weather, or in crossing rivers; a set of carpenter’s tools.
An outfit may be much lightened by having all the provisions and other consumable articles packed in square tin cases, and in boxes and jars of such forms as may render them available for containing specimens. If the traveller is going to the humid regions of the Indian Archipelago, South-Eastern Asia, or tropical America, where excessive moisture, mildew, and ants are great enemies to the naturalist, he should add to his outfit two drying cages, for everything that is not put at once into spirits is liable to be destroyed before it is dry enough to be stowed away in boxes. They may be made of light wood, so arranged as to take to pieces and put together again readily; one for birds should be about 2ft. 6in. long by 1ft. 6in. high, and 1ft. broad; the other for insects and other small specimens may be about one-third less. They should have folding doors in front, having panels of perforated zinc, and the backs wholly of the latter material; the sides fitted with racks to hold six or eight plain shelves, which in the smaller cage should be covered with cork or any soft wood that may be obtained in tropical countries. A strong fixed ring, fastened in the top of the cage, with a cord having a hook attached to the end, by which to hang it in an airy place; it will keep the contained specimens out of harm’s way until they are quite dry, when they may be stowed away in close fitting boxes. If this plan be not adopted, it will be almost impossible to preserve specimens in these countries.
The countries which are now the least known with regard to their natural history are New Guinea and the large islands to the east ofit, Northern Australia, the island of Borneo, Tibet, and other parts of Central Asia, Equatorial Africa, and the eastern side of the Andes, from the east of Bogota to the south of Bolivia.
Collecting.
In most of the better-known countries botany has been better investigated than zoology; and in most countries there still remains much to be done in ascertaining the exact station and the range both vertical and horizontal of known species. This leads us to one point which cannot be too strongly insisted on, namely, that some means should be adopted by the traveller to record the exact locality of the specimens he collects. In the larger-dried animals this may be done by written tickets attached to the specimens; in pinned insects a letter or number may be fixed on the pins of all specimens taken at one place and time, the mark to refer to a note book. The initial letter, or first two or three letters of the locality, is perhaps the readiest plan; and when all the specimens taken at one place can be put into a separate box, one memorandum upon the box itself will be sufficient. Reptiles and fishes can have small parchment tickets attached to them before placing them in spirits. A traveller may be puzzled in the midst of the profusion of animal and vegetable forms which he sees around him, to know what to secure and what to leave. Books can be of very little service to him on a journey, and he had better at once abandon all ideas of encumbering himself with them. A few days’ study at the principal museums before he starts on his voyage may teach him a great deal, and the cultivation of a habit of close observation and minute comparison of the specimens he obtains will teach him a great deal more. As a general rule, all species which he may meet with for the first time far in the interior should be preferred to those common near the civilised parts. He should strive to obtain as much variety as possible, and not fill his boxes and jars with quantities of specimens of one or a few species. But as some of the rarest and most interesting species have great resemblance to others which may be more common, he should avail himself of every opportunity of comparing the objects side by side. In most tropical countries the species found in open and semi-cultivated places are much less interesting than those inhabiting the interior of the forests; and it generally happens that thefew handsome kinds which attract the attention of the natives are species well known in European museums.
In botany, a traveller, if obliged to restrict his collecting, might confine himself to those plants which are remarkable for their economical uses, always taking care to identify the flowers of the tree or shrub whose root, bark, leaves, wood, &c., are used by the natives, and preserving a few specimens of them. But, if he is the first to ascend any high mountain, he should make as general a collection of the flowering plants as possible at the higher elevations. The same may be said of insects found on mountains, where they occur in very great diversity; on the shady and cold sides rather than on the sunny slopes; under stones and about the roots of herbage, especially near springs; on shrubs and low trees, and so forth; for upon a knowledge of the plants and insects of mountain ranges depend many curious questions in the geographical distribution of forms over the earth.
In reptiles, the smaller Batrachia (frogs, salamanders, &c.) should not be neglected, especially the extremely numerous family of tree frogs. Lizards may be caught generally with the insect-sweeping net; the arboreal species, seen out of reach, may be brought down with a charge of dust shot. Snakes should be taken without injuring the head, which is the most important part of the body. A cleft stick may be used in securing them by the neck, and on reaching camp they may be dropped into the jars of spirits. As large a collection as possible should be made of the smaller fishes of inland lakes and unexplored rivers. Dr. Günther, of the British Museum, has authorised me to say that a traveller cannot fail to make a large number of interesting discoveries if he collects a few specimens of the species he meets with in the lakes and rivers of the interior of any country. It can scarcely be expected that specimens of the larger animals can be brought away by a geographical expedition, although some species are still desiderata in the large museums of Europe. Additional specimens of all genera, of which there are numerous closely-allied species (e.g., rhinoceros, antelopes, equus, &c.), would be very welcome for the better discrimination of the species. If only portions can be obtained, skulls are to be preferred. In humid tropical regions, entire skins cannot be dried in time to prevent decay, and it is necessary to place them,rolled up in a small compass, in spirits. The smaller mammals, of which there remain many to reward the explorer in almost all extra-European countries, may be skinned, dried, and packed in boxes in the same manner as birds. The smaller birds shot on an excursion should be carried to camp in the game bag, folded in paper, the wounds, mouth, and anus being first plugged with cotton. Powdered calcined gypsum will here be found very useful in absorbing blood from feathers, on account of the facility with which it can be afterwards cleared from the specimens. All plants, when gathered, are placed in the tin box which the traveller carries with him. Land and fresh water shells may be carried home in a bag. All hard-bodied insects, such as beetles, ants, and so forth should be placed, in collecting, in small bottles, each bottle having a piece of slightly-moistened rag placed within it, to prevent the insects from crowding and injuring each other. The hint previously given, with regard to numbers of specimens, must be repeated here. Take as great a variety of species as possible, the sweeping-net should be freely used (except in very wet weather) in sweeping and beating the herbage and lower trees. In collecting ants, it is necessary to open nests and secure the winged individuals of each species, which must be afterwards kept together with the wingless ones to secure the identification of the species. Bees and wasps may be caught in the net and then placed, by means of small forceps, in the collecting bottle, and afterwards killed in the same way as beetles and other hard-bodied insects. All soft-bodied insects should be killed on capture (by a slight pressure of the chest underneath the wings by thumb and finger), and then pinned in the pocket collecting box. If the traveller has leisure and inclination for the pursuit, he may readily make a large and varied collection of these, and will do good service to science if he notes carefully the exact localities of his captures, altitude above the sea, nature of country, the sexes of the species, if detected, and information on habits. The delicate species should be handled very carefully and put away into the drying cage immediately on return from an excursion. Spiders may be collected in bottles, and afterwards killed and pinned in the same way as other insects. Crustacea (shrimps, crawfish, &c.) in rivers and pools may be collected with the landing net,and afterwards well dried and pinned like hard-bodied insects, except when they are large in size, when their bodies must be opened, and emptied of their contents.
Preserving and packing.
Previous to skinning a small mammal or bird make a note of the colour of its eyes and soft parts, and, if time admits, of the dimensions of its trunk and limbs. It facilitates skinning of birds to break, before commencing, the first bone of the wings a short distance above the joint, which causes the members to lie open when the specimen is laid on its back on the skinning board. The animal should be laid with its tail towards the right hand of the operator, and the incision made from the breast bone nearly to the anus. A blunt wooden style is useful in commencing the operation of separating the skin from the flesh. When the leg is reached, cut through the knee joint, and then clear the flesh from the shank as far as can be done, afterwards washing the bone slightly with arsenical soap, winding a thin slip of cotton round it, and returning it to the skin. Repeat the process with the other leg, and then sever with the broad-bladed scissors the spine above the root of the tail. By carefully cutting into the flesh from above the spine is finally severed without injuring the skin of the back, and it is then easy to continue the skinning up to the wings, when the bones are cut through at the place where they had previously been broken, and the body finished as far as the commencement of the skull. A small piece of the skull is now cut away, together with the neck and body, and the brains and eyes are scooped out, the inside washed with soap, and clean cotton filled in, the eyes especially being made plump. In large headed parrots, woodpeckers, and some other birds, the head cannot thus be cleansed; an incision has therefore to be made either on one side or on the back of the neck, through which the back of the skull can be thrust a little way and then cleansed, the incision being afterwards closed by two or three stitches. The bones then remaining in each wing must be cleansed, but so as not to loosen the quill feathers. It is much better to take out the flesh by making an incision on the outside of the skin along the flesh on the inner side of the wing. The inside of the skin must now be washed with the soap, and a neck of cotton (not too thick)inserted by means of long narrow forceps, taking care to fix the end well inside the skull, and withdrawing the empty forceps without stretching the skin of the neck and thus distorting the shape of the bird. Skins need not be filled up with cotton or any other material, but laid with the feathers smoothed down on the boards of the drying cage until they are ready to be packed in boxes. In very humid climates like that of Tropical America, oxide of arsenic in powder is preferable to arsenical soap, on account of the skins drying quicker, but it cannot be recommended to the general traveller, owing to the danger attending its use.
In mammals the tail offers some difficulty to a beginner. To skin it, the root (after severing it from the spine) should be secured by a piece of strong twine, which should then be attached to a nail or beam. With two pieces of flat wood (one placed on each side of the naked root) held firmly by the hand and pulled downwards, the skin is made rapidly to give way generally to the tip. The tails of some animals, however, can be skinned only by incisions made down the middle from the outside. The larger mammal skins may be inverted, and, after washing with soap, dried in the sun; and, as before remarked, it is often necessary to roll them up and preserve in spirits. The skins of small mammals and birds, after they arequitedry, may be packed in boxes, which must be previously well washed inside with arsenical soap, lined with paper, and again covered with a coating of the soap, and well dried in the sun. This is the very best means of securing the specimens from the attacks of noxious insects, which so often, to the great disgust of the traveller, destroy what he has taken so much pains to secure. Where wood is scarce, as in the interior of Africa, boxes may be made of the skins of antelopes, or other large animals, by stretching them when newly stripped from the animal over a square framework of sticks, and sewing up the edges after being dried in the sun; they make excellent packing-cases. With regard to reptiles and fishes, I cannot do better than quote the following remarks sent to me by Mr. Osbert Salvin, who collected these animals most successfully in Guatemala:—"Almost any spirit will answer for this purpose, its fitness consisting in the amount of alcohol contained in it. In all cases it is best to procurethe strongest, being less bulky, and the water can always be obtained to reduce the strength to the requisite amount. When the spirit sold retail by natives is not sufficiently strong, by visiting the distillery the traveller can often obtain the first runnings (the strongest) of the still, which will be stronger than he requires undiluted. The spirit used should be reduced to about proof, and the traveller should always be provided with an alcoholometer. If this is not at hand, a little practice will enable him to ascertain the strength of the spirit from the rapidity with which the bubbles break when rising to the surface of a small quantity shaken in a bottle. When the spirit has been used, this test is of no value. When animals or fish are first immersed, it will be found that the spirit becomes rapidly weaker. Large specimens absorb the alcohol very speedily. The rapidity with which this absorption takes place should be carefully watched, and in warm climates the liquid tested at least every twelve hours, and fresh spirit added to restore it to its original strength. In colder climates it is not requisite to watch so closely, but practice will show what attention is necessary. It will be found that absorption of alcohol will be about proportionate to the rate of decomposition. Spirit should not be used too strong, as its effect is to contract the outer surface, and thus closing the pores prevent the alcohol from penetrating through to the inner parts of the specimen. The principal point, then, is to watch that the strength of the spirit does not get below a certain point while the specimen is absorbing alcohol when first put in. It will be found that after two or three days the spirit retains its strength; when this is the case, the specimen will be perfectly preserved. Spirit should not be thrown away, no matter how often used, so long as the traveller has a reserve sufficient to bring it back to its requisite strength. In selecting specimens for immersion, regard must be had to the means at the traveller’s disposal. Fish up to 9in. long may be placed in spirit with simply a slit cut to allow the spirit to enter to the entrails. With larger specimens it is better to pass a long knife outside the ribs, so as to separate the muscles on each side of the vertebra. It is also as well to remove as much food from the entrails as possible, taking care to leave all these in. The larger specimens can be skinned, leaving, however, the intestines in,and simply removing the flesh; very large specimens preserved in this way absorb very little spirit. All half-digested food should be removed from snakes and animals. In spite of these precautions specimens will often appear to be decomposing, but by more constant attention to re-strengthening the spirit they will in most cases be preserved. A case (copper is best) with a top that can be unscrewed and refixed easily, should always be carried as a receptacle; the opening should be large enough to allow the hand to be inserted. This is to hold freshly caught specimens. When they have become preserved they can all be removed and soldered up in tin or zinc boxes; zinc is best, as it does not corrode so easily. The traveller will find it very convenient to take lessons in soldering, and so make his own boxes. (For directions for soldering, seep. 210of this work.) If he takes them ready made they had best be arranged so as to fit one into another before they are filled. When moving about, all specimens should be wrapped in calico, linen, or other rags, to prevent their rubbing one against the other. This should also be done to the specimens in the copper case when a move is necessary, as well as to those finally packed for transportation to Europe. These last should have all their interstices between the specimens filled in with cotton wool or rags. If a leak should occur in a case, specimens thus packed will still be maintained moist, and will keep some time without much injury. Proof spirit should be used when the specimens are finally packed, but it is not necessary that it should be fresh. Land and fresh-water shells, on reaching camp, should be placed in a basin of cold water to entice the animals out, and then, after draining off, killed by pouring boiling water over them. They may be cleansed of flesh by means of a strong pin or penknife. The operculum or mouthpiece of all shells which possess it should be preserved and placed inside the empty shell. Each shell when dry should be wrapped in a piece of paper and the collection packed in a box well padded with cotton or other dry and elastic material.
“The insects collected on an excursion should be attended to immediately on arrival in camp. When leisure and space are limited all the hard-bodied ones may be put in bottles of spirit, and each bottle when nearly full should be filled up to the cork with a piece ofrag, to prevent injury from shaking. Many species, however, become stained by spirit, and it is far better in dry countries, such as Africa, Australia, and Central Asia, to preserve all the hard bodied ones in a dry state in pill boxes. They are killed whilst in the collecting bottles by plunging for a few minutes the bottom half of the bottles in hot water. An hour afterwards the contents are shaken out over blotting paper and put into pill boxes, the bottoms of the boxes being padded with cotton, over which is placed a circular piece of blotting paper. The open pill boxes should then be placed in the drying cage for a day or two, and then filled up with more cotton, the layer of insects being first covered with a circular piece of paper.[C]The soft bodied specimens which are brought home pinned, should be stuck in the drying cage until they are dry, and then pinned very close together in the store boxes. The store boxes both bottom and sides should each have inside a coating of arsenical soap before they are corked, and as they become filled one by one should be washed outside with the soap and pasted all over with paper. Camphor and other preservatives are of little or no use in tropical climates. In some countries where the traveller may wish to make a collection of the butterfly fauna, the best way is to preserve all the specimens in little paper envelopes. He should be careful not to press the insects too flat, simply killing them by pressure underneath the breast, folding their wings carefully backwards and slipping them each into its envelope. In very humid tropical countries, such as the river valleys of tropical America and the islands of the Eastern Archipelago, the plan of stowing away even hard-bodied insects in pill boxes does not answer on account of the mould with which they soon become covered. There are, then, only two methods that can be adopted; one, preserving them at once in spirits, the other, pinning all those over a quarter of an inch long (running the pin through the right wing case, so as to come out beneath between the second and third pair of legs), and gumming those of smaller size on small sheets of card, cut of uniform size, so as to fit perpendicularly in racked boxes like those used to contain microscopical slides butlarger. The cards may be a few inches square, and each may hold several scores of specimens very lightly gummed down a short distance apart. After the cards are filled they should be well dried, and the box containing them washed outside with arsenical soap, and pasted over with paper. All the pinned specimens should be placed to dry for a few days in the drying cage, and afterwards pinned very close together in the cork store boxes.
“Plants are dried by pressure, by means of the boards and straps, between sheets of botanical drying paper, the paper requiring to be changed three or four times. When dry the specimens may be placed between sheets of old newspapers, together with notes the traveller may have made upon them, each placed upon the object to which it refers. Bundles of papers containing plants are not of difficult carriage, but they require to be guarded against wet, especially in fording rivers and in rainy weather, and should be wrapped in skins or India rubber sheeting until they can be safely packed in wooden boxes and despatched to Europe.
“Seeds may be collected when quite ripe, and preserved in small packets of botanical paper with numbers written on them, referring to preserved specimens of the flowers.
“Dry fruits and capsules should be collected when in countries not previously explored by botanists, if the traveller has means of identifying the species to which they belong.
“The collection of fossils and minerals, except in the case of the discovery of new localities for valuable metals, is not to be recommended to the traveller if he is not a geologist. Fossils from an unexplored country are of little use unless the nature and order of superposition of the strata in which they are found can be at the same time investigated. In the cases, however, of recent alluvial strata on the supposed beds of ancient lakes, or deposits in caves, or raised sea beaches containing shells or bones of vertebrate animals, the traveller will do well to bring away specimens if a good opportunity offers. If the plan of the expedition includes the collection of fossil remains, the traveller will of course provide himself with a proper geological outfit and obtain the necessary instructions before leaving Europe.”
Whilst engaged in collecting the beautifully formed and delicateshells found adhering to the minute asperities formed by the process of disintegration on the roofs of the crypts formed by the ancient Tauro-Scythian tribes, we proceeded as follows: After the discovery of an almost crystalline specimen we prepared a soft bed for its reception by arranging in nest form a very soft silk handkerchief in our well worn forage cap, the gold band of which served as a sort of hoop of support. Thus arranged, the nest was held exactly under the fossil shell, which was in most cases freed from its attachments by a single sharp and well directed blow from our pick head on the heel of a sharp well-tempered steel chisel (old files make the best). As the specimens were one by one taken from the cap-nest they were arranged carefully layer after layer in old preserved meat tins, bran being liberally sprinkled in over each distinct layer of shells. On the tin being nearly filled, more bran was added until the packing was firm and complete, the round tin cover was then forced in until about a quarter of an inch from the upper rim of the tin. A few cuts here and there in the tin with a pair of cutting nippers admitted of the turning in of a number of clip pieces by bending the cut tin in elbow form over the cover. These tins when duly numbered and noted were packed in a sixty-gallon barrel with fine soft hay made from steppe grass. The collections thus packed reached England in a perfect state of preservation.
In situations where old preserved meat tins cannot be obtained, large joints of bamboo, or the thin earthen pots used by natives, might be made available for depositing very fragile specimens in. Fine sawdust will answer nearly as well as bran for packing powder; rotten wood from an old decaying log may be rubbed between the hands into fine dust, and made use of for the same purpose. “All collections made in tropical countries should be sent to Europe with the least possible delay, as they soon become deteriorated or spoilt, unless great care is bestowed on them. Dry skins of animals and birds may be packed in wooden cases, simply with sheets of paper to separate the skins. Shells and skulls should be provided with abundance of elastic padding, such as cotton. The boxes containing insects and crustacea should be placed in the middle of large boxes, surrounded by an ample bed of hay, or other light, dry, elastic material; if this last point be not carefully attended to, it will bedoubtful whether such collections will sustain a voyage without much injury. Travellers have excellent opportunities of observing the habits of animals in a state of nature, and these hints would be very deficient were not a few words said upon this subject. To know what to observe in the economy of animals is in itself an accomplishment, which it would be unreasonable to expect the general traveller to possess, and without this he may bring home only insignificant details, contributing but little to our stock of knowledge. One general rule, however, may be kept always present to the mind, and this is that anything concerning animals which bears upon the relations of species to their conditions of life is well worth obtaining and recording. Thus, it is important to note the various enemies which each species has to contend with, not only at one epoch in its life, but at every stage from birth to death, and at different seasons and in different localities; the way in which the existence of enemies limits the range of a species should be also noticed. The inorganic influences which inimically affect species, especially intermittently (such as the occurrence of disastrous seasons), and which are likely to operate in limiting their ranges, are also important subjects of inquiry. The migrations of animals, and especially any parts where the irruption of species into districts previously uninhabited by them, are well worth recording. The food of each species should be noticed; and if any change of customary food is observed, owing to the failure of the supply, it should be carefully recorded. The use in nature of any peculiar physical conformation of animals, the object of ornamentation, and so forth, should be also investigated wherever opportunity occurs. Any facts relating to the interbreeding in a state of nature of allied varieties or the converse—that is, the antipathy to intermingling of allied varieties—would be extremely interesting. In short, the traveller should bear in mind that facts having a philosophical bearing are much more important than mere anecdotes about animals. To observe the actions of the larger animals a telescope or opera-glass will be necessary, and the traveller should bear in mind, if a microscope is needed in his journey, that, by reversing the tubes of the telescope, in which all the small glasses are contained, a compound microscope of considerable power is produced.”