PUBLIC RECORD OFFICE
Reference :-
TTILL CO.
.885
ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH-NOT TO
18 PUBLIC RECORD OFFICE, LONDON
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Main triangulation chains.-Instrument 8-inch micrometer theodolite.
Triangular errors mean, 2 secs. of arc.
maximum, 6 secs, of arc.
Lengths of sides, 10-30 miles.
Topographical triangulation.-Instruments 6-inch or 5-inch micrometer
theodolites.
Triangular errors mean, 6 secs. of arc.
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maximum, 24 secs. of arc.
Lengths of sides, 6-10 miles.
All points should be computed in geographical co-ordinates, but no square" adjustment need be made.
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At present the topographical triangulation is done by the trigonometrical branch. When the topographical section is constituted the officers of that branch should take over this work. In districts where cadastral maps are required the necessary tertiary triangulation should be done by the cadastral branch.
The computation forms and angle books used should be those issued by the School of Military Engineering, as printed in the "Text Book of Topographical Surveying" Complaint has been made that the angle books are not large enough to allow of the convenient insertion of the figures. As it is of considerable import- ance that all African surveys should use the same forms, it is recommended that these angle books should be continued in use notwithstanding this objection to them. When they are reprinted any criticisms, based upon the experience of the East African Survey Department, can be given due weight.
Topographical Work.
No topographical section yet having been constituted the only work of this class that has been accomplished is a preliminary map of the Sotik district, on a scale of 1/250,000, done by the non-commissioned officers of the trigonometrical section. This map will be printed and will meet all requirements for many years.
It is, however, impossible to carry on systematic topography in this way, especially of the more settled parts of the country where maps on a larger scale are called for.
The early formation of a full topographical section, of two officers and six or eight surveyors, is imperative.
The measurement of the base near Nairobi will probably be completed before the rains, due at the end of March, so that the triangulation can begin immediately after them, say in June. By September the work will have advanced far enough to enable the topographers to start, so that if a topographical section could be employed for half the financial year 1907-8 good progress could be made.
Failing this the section must be appointed for 1908-9. In this case they could not begin mapping until June, 1908, and it is quite improbable that the first sheet of the map would be issued before January, 1909.
There is no advantage to be gained by drawing up an elaborate programme of the order in which the districts should be mapped. Any such scheme is liable to be totally falsified by the development of the Colony upon unexpected lines and by the opening up of fresh areas to settlement.
The only general principles to lay down are that the mapping should be strictly completed by sheets, and that it should be started in the more closely-populated parts of the country, i.e. :—
Nairobi to Fort Hall.
Round Naivasha, Nakuru and Kisumu.
The coast belt at Mombasa.
The general scale for the settled parts should be 1/125,000 (1⁄2 inch to 1 mile. nearly) with possibly a few areas of special importance mapped upon the 1/62,500 scale (1 inch to 1 mile, nearly), and with a reduction of scale to 1/250,000 (4 inch to 1 mile, nearly) for forest, uncultivated and sparsely-populated tracts.
The 1/125,000 sheets can be either 45 minutes of longitude by 30 minutes of latitude or 30 minutes square (174 inches on the paper) as may be preferred. For the 1/250,000 sheets it would be better to adhere to the War Office Index and make
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them 14 degrees of longitude by 1 degree of latitude. The general style of the finished maps should follow the standard form, i.e. :-
Sheets bounded by meridians and parallels. Projection Rectangular polyconic.
Contours at 100 feet vertical intervals (for 1/125,000 scale). Colours: Black for lettering and detail.
Blue for water.
Brown for contours and heights.
Green for forests.
Scales of both miles and kilometres.
The annual output of work that should be expected from a topographical section of six plane-tablers may be put at 4,800 square miles, or four sheets of map each
30 minutes (35 miles) square. If all the topographers are provided with ponies or mules these figures will be increased by 30 to 50 per cent.
It must be noted that the general scheme now put forward for the organization of the Survey Department, namely, one trigonometrical and one topographical section, cannot be taken as a permanent one, for the reason that the relative strength of the two branches is disproportionate, and if this disproportion is continued the triangulation will run ahead of the topography. This disparity is of no importance at first, but after a few years it will lead to the disadvantage that the topographers will be so far behind the triangulators that the signals may have been blown down, decayed, or otherwise destroyed, thus causing extra work and expense in replacing them.
The composition of the Survey Department should therefore be re-cast at the end of four or five years from the present date. At that time the option will lie between reducing the trigonometrical or increasing the topographical party, a choice which can only be decided in view of the material progress of the Protectorate. If prosperous and if land is being rapidly taken up and put under profitable cultiva- tion the decision will naturally be for accelerating the production of maps. Should, however, the advance of the Colony be less rapid than its well-wishers hope, the first-named alternative might have to be faced.
Cadastral Work.
Up to the spring of 1906 all the cadastral or revenue survey required for the laying out of new estates and the preparation of the necessary deeds devolved upon the Land and Survey Office.
This office was much understaffed and the work fell into serious arrear, for details and examples of which Captain Smith's report may be consulted. Apart from the understaffing several other causes of delay may he noted. First and perhaps foremost among these must be put the fact that the unsound practice has been followed by selling blocks of land as containing a certain specified number of acres instead of as marked out upon the ground. Suppose a farmer wishes to acquire farm of 640 acres. It is of no vital importance to him whether the area is 650 or 630 or even 610 acres; what is important is that he should have his ground plainly marked out by boundary posts and that the definitive deed conveying the land to him should be delivered with the minimum of delay. When this is done he is in a position to fence his land, should he so desire, or if he wishes to dispose of it he can cut it up or transfer it as a whole. Should the purchaser be of such an exacting nature that he wants precisely the 640 acres, neither more nor less, then it is clearly his business to get it surveyed on his own behalf and at his own expense. To demand that a small establishment should undertake the survey of isolated patches of land, situated all over the country, executed with such a degree of precision that the plans show the exact acreage is setting it an almost impossible task, and, in any case, one that could not be accomplished without a staff entirely out of the present question. Yet this is precisely the demand that has been made upon the Survey and Land Office in the past. To remedy this state of affairs is not difficult. The actual wording of the deeds contains no explicit or implied guarantee of the acreage, and to prevent any misunderstanding it is only necessary that steps should be taken to bring home clearly to the intending purchaser that it is land included between certain boundary marks that he is buying, and that the acreage is only mentioned as a guide and not as a guarantee of the quantity of land lying inside the marks. It would further be well that a note should be either added to
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