Astronomical observation, and we think it is but too evident, which is the one most likely to give the best results.

In the preparation of main circuits, where a large river forms the boundary on one side, the stations should be taken along one side only, and when the adjoining main circuit is prepared on the opposite side of the river, its stations should run on the opposite side, leaving the river to form a circuit of itself; if this is not done, and the stations on one side of the river are made common to both circuits, it involves the necessity of crossing the river every time a village has to be closed on a main circuit station which is not always practicable.

Also, should the work of the season not extend beyond the river, it is only necessary to preserve the two extreme stations on the river to connect the work of the next season, and we therefore advise that a river should always be made the boundary of a main circuit, even should it not be the boundary of the Pergunnah; there is no more objection to dividing a Pergunnah into two circuits, than there is to enclosing two or three small Pergunnahs within one main circuit; and a river offers many facilities in this country, to laying down by intersection prominent points, such as mosques, temples, &c. which are often found on their banks, and perhaps not visible from the interior part of the Pergunnah.

If it becomes necessary to cross the river during the progress of the main circuit, the distance across should invariably be triangulated and the base of the triangle ought always to be at least one-third of the estimated distance. The Tindal who prepares the main circuit should always clear a line for a base, whenever it is necessary to cross a river, and not leave it to be done at the time of survey; this man must also take the leading flag during the survey of his circuit, for being acquainted with all the stations, much valuable time is saved, which would otherwise be lost, were the leading flag taken on by a classie who had to hunt out every station.

It is absolutely essential that these main circuits should be surveyed with the greatest care, and the computations carried on under the Superintending Officer's own eye. Instruments of not less than 7 inch diameter should be specially set aside for this purpose, and on no account ever entrusted to the Native Assistants. The carrying out of this system, in all its integrity, is most strongly insisted on by the Departmental Rules. The main circuits are intended to free the general results from the accumulation of error, which otherwise would necessarily be engendered by building up one small polygon on another; they should therefore never enclose a less area than 50 square miles, and they may average from that to 100 square miles.

It may be perfectly easy, instead of making a bonâ fide circuit of this description in the field, to extract the sides of all the exterior villages bordering on a Pergunnah, and manufacture a traverse of the required description, and so evade the real intent and meaning of the order, merely for the sake of the slight extra trouble caused in going round a main circuit. The inefficient supervision over Assistants will cause this, and as the consequences are most fatal to the value and character of a survey, too much care cannot be observed to guard against it, the proof of the work never can come out so satisfactory, and therefore it is liable to accumulate error beyond the means of reducing it within the allowed correction.

Each part of the work is rendered independent by these means: the larger circuits being measured with greater care and precision and with larger instruments than the smaller, the errors are not only detected and made apparent, but they can be confined within the space wherein they were generated, merely by dispersing the error of the subdivisions or village circuits, of which they are composed.

CHAPTER XIII.

ON THE METHOD OF PREPARING AND SURVEYING VILLAGE CIRCUITS, AND FILLING IN TOPOGRAPHICAL DETAILS.

SIMULTANEOUSLY with the preparation of the main circuits, line-cutters are detached for the village circuits, and they proceed to prepare their villages for survey as shown in Chapter XI. No definite rules can be laid down for their guidance as to where they should commence their work, as it depends very much on the size and shape of the Pergunnah or main circuit; as a general rule, they should be told off to main circuits in the proportion of one party to every fifty villages contained within the circuit, thirty villages being considered a fair month's work for one line-cutting party.

Some Surveyors prepare their villages for survey by commencing from the main circuit Stations and working inwards towards the centre of the Pergunnah; others, the reverse, commencing from the centre, and working on to the main circuit, and there closing their work: the latter is, however, preferable; the former is dependant on the main circuit Stations being previously prepared, which cannot always be the case, whereas in the latter, the village line-cutter only requires the main circuit stations to close the several villages situated on the boundary of the Pergunnah.

A little practice in the field will soon show a Surveyor the best method of telling off his line-cutters, the only care required, being that of taking up or closing on one another's Station

points in adjoining villages, and of limiting their offsets within the prescribed maximum of 5 Chains on each side of the chain line.

A sufficient number of circuits being thus marked out, and all the stations duly prepared ahead of the surveying party, the mode of proceeding will be best explained by an example

In the adjoining Plate VI., let the Station lines GF, JA, AB, and BC, be four lines previously surveyed on a main circuit, and the three enclosures marked 1, 2 and 3, be the irregular figures formed by the boundaries of the villages contained within them.

For the survey of village No. 1, or Mahmoodpore, start from Station C of the main circuit, observe the interior angle BCa, thence proceed to Stations a, b, c, d, e, observing the interior angles of the polygon Cab, abc, bcd, &c., measuring the lines Ca, ab, bc, cd, &c., and closing on Station J of the main circuit, observing the interior angle eJA; to complete the angles of this polygon, to obtain the necessary proof, the angles JAB and ABC of the main circuit must be added to the angles above taken.

To survey the village of Patpore, No. 2, commence from Station c of No. 1, Mahmoodpore, observe the interior angle dca, and proceed round measuring the several lines and keeping the village itself to the left-hand, observing the interior angles cab, abc, &c., and closing on Station G of the main circuit, observing the angle cGJ; to complete the interior angles of this polygon, the angle GJe is required, obtainable by deducting the angle eJA of No. 1, Mahmoodpore, from the main circuit angle GJA, and also the angles Jed and edc, obtainable by reversing the angles deJ and cde in the adjoining village, No. 1.

For the survey of No. 3, or Jehanabad, commence at Station a, of No. 1, Mahmoodpore, observe the interior angle baa and proceeding round through the Stations a, b, c, d, as before, close