Makeshift Clinometer.

Captain Lendy recommends a simple form of clinometer, which is constructed as follows: The clinometer consists of a quadrant of pasteboard or of brass, having a plummet, A H, suspended at its centre, and graduated, as in the diagram, on both sides. When we require an angle of elevation, we look along the edge, A C, till B is in sight, when the plummet indicates the angle. For an angle of depression reverse the instrument. This instrument is an excellent substitute for the ordinary form of sextant in case of accident or breakage.

The same officer describes an ingenious substitute for an ordinary water level, which can always be replaced by a little ruler, A B, suspended by strings, C A, C B, having a little weight under it to prevent the wind from shaking it. When held by the string the line A B will give a horizontal direction. To make use of it for levelling along A B, start from A, hold the ruler up to the eye, and, aiming along its edge, notice to what point (B) of the ground the visual ray corresponds. Repair there, we shall have ascended a distance—the height of the eye above the ground. Start afresh from B, and in this manner the number of stations made between A and B, multiplied by the height of the eye above ground, will give the difference of level required.

The same author gives the following useful hints on the estimation of distance: “Pacing is generally resorted to while filling in the details of a survey. The trotting of a horse might also be made available. Distances can also be measured by time when we have previously ascertained over how many yards we walk or ride in a given time. This is not a rare occurrence in the field. When distances are measured by pacing or riding a correction is necessary, owing to the lengthening caused by acclivities and the turnings of roads. On slightly uneven ground we subtract 1-7th of the distance paced, and 1-5th when the inductions are more important.”

When the atmosphere is even sound travels at the rate of 1118ft. per second; therefore a musket fired may serve to measure a distance. A watch gives the number of seconds elapsed between the instant the light is seen and that when the report is heard; that number, multiplied by 1118ft., gives very approximately the distance. If no watch is to be had the time is obtained by counting the pulsations of an artery. A sound pulse averages from 75 to 80 in a minute. Distances may even be guessed by observing that in clear weather the windows of a house can be counted at 4000yds. Horses and men appear as dots at 2200yds. A horse is clearly seen at 1200yds. The movements of men are perceived at 800yds.; and the head is distinctly visible at 400yds.

For the measurement of time, as we have said before, a thoroughly well-made English lever watch is preferable to a chronometer, as it will withstand the rough jolts and vibrations caused by being carried on horseback, or in a waggon, far better. Sun-dials, properly so called, are rarely of much use to the traveller; still the pocket compass may be made to do duty as an indicator of time. There is a small and very portable little instrument to be obtained of most opticians, in the formation of which a silk cord is so attached to the border of the compass case that on adjusting the compass, so that the needle shall point to a black stud inserted for the purpose, a shadow is cast by the silk on the figure indicating the hour of the day. A small equation table is attached to the inside of the cover.

When no watch is at hand seconds can be indicated closely enough for practical purposes by suspending a small bag of shot or bullets from the end of a piece of fine fishing line or copper wire. Attach the upper end to a cross bar, laid in the crutches of two forked sticks, let the bag hang, and regulate the length of the string until you find that it describes the proper arc in swinging; your own pulse, the number of which has been already given, or that of a horse, which may be roughly set down as thirty-six beats per minute, will be a sufficient guide. If great accuracy is sought, recourse may be had to repeated astronomical observations.

An excellent makeshift hour-glass can be made from two empty soda-water bottles, and a little fine dry sand. A wooden plug of 3in. long should be so cut as to fit the necks of the bottles tightly. Through the centre of the plug, from end to end, burn with a red-hot wire a fine even hole, then with your pocket-knife make a funnel-shaped or flared-out mouth to each hole, cutting away until the extreme edge of the plug is reached. See that your sand is free from small stones or lumps, pour it into one of the bottles, insert the plug half-way, and test the quantity by letting it run out at the hole. When you have the proper charge to run for fifteen or thirty minutes, place the bottles mouth to mouth in such a way that one-half the plug shall be in the neck of each bottle. A bit of raw hide sewn round the union of the bottle mouths makes all secure. The joined bottles can then be mounted in a wooden frame for use. Two bits of flat square board, with holes in the centre for the bottoms of the bottles to come partly through, pinned at the corners by four bars of wood, is as good a form of frame as any.

The Malays make use of a very convenient and simple form of time indicator or water clock, which is made as follows:—A large-sized cocoa-nut shell is obtained; this is first scraped perfectly smooth, and then at the bottom a very minute hole is bored. The nutshell is then set floating in a pail of sea water. As the shell fills it gradually settles deeper and deeper, and at last sinks to the bottom with a gurgle and a thud. The rapidity of filling, and consequent duration of time, is regulated by increasing or diminishing the size of the orifice. Thus a man may be set to keep a two-shell watch or a four-shell watch, and so on. The instant the shell sinks to the bottom of the pail it attracts attention by the disturbance made. It is then immediately taken up, the water is poured out, and it is set afloat again. Excellent time can be kept by this primitive arrangement.

For ascertaining the altitude of high lands, ranges of hills or mountains, a thoroughly good “compensated” aneroid barometer should be taken. This will not only be valuable for measurements, but will be of considerable service in the observation of weather signs. We have one now in use made expressly for us by Mr. Cary, of 181, Strand. It is protected by a smooth wooden cover or case, enveloped in tightly-stretched leather. A sling is fitted to it by a swivel loop, which admits of its being carried over the shoulder or in the jacket pocket. The Table of Altitudes, given on the next page, will prove a useful guide when conducting observations with it.

Table of Altitudes.

Aneroid or Corrected Barometer.	Height in Feet.	Aneroid or Corrected Barometer.	Height in Feet.	Aneroid or Corrected Barometer.	Height in Feet.
in.	ft.	in.	ft.	in.	ft.
31·00	0	26·76	4000	23·11	8000
30·94	50	26·76	4050	23.07	8050
30·88	100	26·67	4100	23.03	8100
30·83	150	26·62	4150	22.98	8150
30·77	200	26·57	4200	22·94	8200
30·71	250	26·52	4250	22·90	8250
30·66	300	26·47	4300	22·86	8300
30·60	350	26·42	4350	22·82	8350
30·54	400	26·37	4400	22·77	8400
30·49	450	26·33	4450	22·73	8450
30·43	500	26·28	4500	22·69	8500
30·38	550	26·23	4550	22·65	8550
30·32	600	26·18	4600	22·61	8600
30·26	650	26·13	4650	22·57	8650
30·21	700	26·09	4700	22·52	8700
30·15	750	26·04	4750	22·48	8750
30·10	800	25·99	4800	22·44	8800
30·04	850	25·94	4850	22·40	8850
29·99	900	25·89	4900	22·36	8900
29·93	950	25·85	4950	22·32	8950
29·88	1000	25·80	5000	22·28	9000
29·82	1050	25·75	5050	22·24	9050
29·77	1100	25·71	5100	22·20	9100
29·71	1150	25·66	5150	22·16	9150
29·66	1200	25·61	5200	22·11	9200
29·61	1250	25·56	5250	22·07	9250
29·55	1300	25·52	5300	22·03	9300
29·50	1350	25·47	5350	21·99	9350
29·44	1400	25·42	5400	21·95	9400
29·39	1450	25·38	5450	21·91	9450
29·34	1500	25·33	5500	21·87	9500
29·28	1550	25·28	5550	21·83	9550
29·23	1600	25·24	5600	21·79	9600
29·17	1650	25·19	5650	21·75	9650
29·12	1700	25·15	5700	21·71	9700
29·07	1750	25·10	5750	21·67	9750
29·01	1800	25·05	5800	21·63	9800
28·96	1850	25·01	5850	21·59	9850
28·91	1900	24·96	5900	21·55	9900
28·86	1950	24·92	5950	21·51	9950
28·80	2000	24·87	6000	21·47	10000
28·75	2050	24·82	6050	21·44	10050
28·70	2100	24·78	6100	21·40	10100
28·64	2150	24·73	6150	21·36	10150
28·59	2200	24·69	6200	21·32	10200
28·54	2250	24·64	6250	21·28	10250
28·49	2300	24·60	6300	21·24	10300
28·43	2350	24·55	6350	21·20	10350
28·38	2400	24·51	6400	21·16	10400
28·33	2450	24·46	6450	21·12	10450
28·28	2500	24·42	6500	21·08	10500
28·23	2550	24·37	6550	21·05	10550
28·18	2600	24·33	6600	21·01	10600
28·12	2650	24·28	6650	20·97	10650
28·07	2700	24·24	6700	20·93	10700
28·02	2750	24·20	6750	20·89	10750
27·97	2800	24·15	6800	20·85	10800
27·92	2850	24·11	6850	20·82	10850
27·87	2900	24·06	6900	20·78	10900
27·82	2950	24·02	6950	20·74	10950
27·76	3000	23·97	7000	20·70	11000
27·71	3050	23·93	7050	20·66	11050
27·66	3100	23·89	7100	20·63	11100
27·61	3150	23·84	7150	20·59	11150
27·56	3200	23·80	7200	20·55	11200
27·51	3250	23·76	7250	20·51	11250
27·46	3300	23·71	7300	20·47	11300
27·41	3350	23·67	7350	20·44	11350
27·36	3400	23·62	7400	20·40	11400
27·31	3450	23·58	7450	20·36	11450
27·26	3500	23·54	7500	20·32	11500
27·21	3550	23·50	7550	20·29	11550
27·16	3600	23·45	7600	20·25	11600
27·11	3650	23·41	7650	20·21	11650
27·06	3700	23·37	7700	20·18	11700
27·01	3750	23·32	7750	20·14	11750
26·96	3800	23·28	7800	20·10	11800
26·91	3850	23·24	7850	20·07	11850
26·86	3900	23·20	7900	20·03	11900
26·81	3950	23·15	7950	19·99	11950
26·76	4000	23·11	8000	19·95	12000

This Table is intended more particularly for the graduation of aneroids with a circle of measures in feet concentric with the ordinary circle of barometric height measured in inches. The circle of feet is to be read off, at the upper and lower stations, by the index; and the rule for measuring the height will be: Subtract the reading at the lower station from the reading at the upper station; the difference is the height in feet.

Example.

	In.	Ft.
Barometer at Upper Station,	23·50	7550
” Lower ”	24·20	6750
Actual height		800
There is no correction for temperature required with aneroids which are “compensated.”

In using the instrument here described in the measurement of altitudes, the movable needle point which is turned by the mill-edged rim is set opposite the index hand. This is to be done at the foot of the mountain or hill. Then the difference between the index hand and the movable needle point will be the number of feet ascended (vide Table appended, and “Example”). Suppose the index hand stand when at the foot of the hill at 30in. ¹⁰⁄₁₀₀, and when you again look at the instrument you find the index hand has gone back, or has fallen to 29in. ¹²⁄₁₀₀, then you would have ascended 900ft.

At [page 26] of this work we referred to the hypsometrical or boiling-point apparatus used in taking altitudes. Since the remark there made was penned we have endeavoured, and we hope successfully, to so guard the improved form of aneroid barometer, referred to at p. 741, from the chance of accident, that it can be safely carried by the explorer of even the most rugged and inhospitable regions.