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written chiefly for my own pleasure and improvement, when surveying, plotting, &c.; and every thing connected with practical measuring which came under my notice was minutely observed in the particular order in which it was done; so that every thing worth observing in the business of practical land-surveying has been carefully examined, and no pains and expense have been spared to render the work suitable to the capacity of learners.

My original design was to treat only of landsurveying, but on mature consideration I deemed it right to make the work more extensively useful, by adding artificers' work, conic sections, gauging, plane trigonometry, levelling, and mensuration of solids and superficies, the whole of which is divided into fifteen books, as follows:

Book I. contains definitions and properties of superficial figures, which are chiefly selected from Simpson's and Emerson's Geometry.

Book II. contains a full description and use of the instruments employed in land-surveying and plotting, with directions in keeping the field-book, and every necessary information in setting out lines, and measuring and plotting single fields. It may be well to notice that the sketchings of the fences are not given to the field notes in the subsequent part of this work, to avoid increasing the expensiveness of the book with the necessary copper-plates; but, in practice, the sketchings of fences are always drawn or sketched as represented in plate II. The pupil will here find more practical directions in measuring lines, fences, fields, and in the methods of proving the correctness of the measure of single fields, than are to be found in any other similar work.

Book III. treats of plotting such figures as are measured to obtain the plan; and if this be well understood by the pupil, he will find little difficulty in drawing the plan of an estate, as every estate is plotted upon similar principles.

Book IV. treats of the mensuration of superficies. In this part I have added only such figures as are commonly met with in practice; there is also inserted the perch table which is of peculiar use to the landsurveyor; and a more practical method is shown for measuring a field which appears to the eye to be square, than by placing the cross-staff in the corners, as commonly taught in books of mensuration.

Book V. treats of measuring single fields with the chain and cross-staff; and also of the mode of reducing the hypothenusal measure of hilly ground to that of the horizon, being much more simple and better adapted to practical purposes, than that by the use of a quadrant, as usually recommended by writers on land-surveying. There is likewise given the method of proving the accuracy of the measure of a field by taking the contrary diagonal and perpendiculars, which is not noticed by previous writers on the subject.

Book VI. contains the whole art of casting or measuring a field by its plan, as practised by professional men; and of reducing customary measure to statute, and vice versa, by obtaining a common multiplier, which gives the answer in half the time required for the common method.

Book VII. comprises the whole art of measuring and proving single fields, meres, woods, rivers, roads, moors, ings land, open field lands, and small estates, as now used by practical land-surveyors; and of also

copying and reducing plans by various methods. In this part of the work no pains have been spared to render the art of land-surveying easy, pleasant, and certain, so that the young survey or may readily comprehend the whole art, and be able to reduce it to practice without any help from a practical man.

Book VIII. contains the complete art of measuring, plotting, numbering, casting, and obtaining particulars of large estates, towns, villages, &c.; with instructions as to the best methods of colouring and embellishing maps. In measuring estates I have taken every possible pains to obviate all difficulties which a learner meets with in practice, so as to render the art of measuring large estates easy to be acquired without the assistance of a practical teacher. In colouring and embellishing maps I have adopted the methods practised by professional men, in preference to those practised at schools.

Book IX. contains information on the division of land, or the whole art of staking out fences; and of partitioning a given area into a variety of figures; here also is shown how to divide a field among different claimants according to their respective interests, and to cut off a piece of land worth a given value. In this part of the work the author flatters himself that much original and practical information will be found relating to division of land and of an inclosure, with several examples never before published.

Book X. treats of mensuration of solids, hay stacks, excavations of drains, and embankments; description. and use of the carpenters' rule, timber measure, &c. The solid figures are drawn upon a new and improved plan, and there is added every necessary direction for taking these dimensions, as adopted by practical men.

Book XI. treats of the measuring of artificers' work, viz., bricklayers', masons', carpenters' and joiners', slaters' and tilers', plasterers', paviors', painters', glaziers', and plumbers'; together with rules for measuring vaulted roofs, domes, groins, and saloons. This part has been submitted to the inspection of several builders, to whom I am indebted for much practical information in measuring buildings, &c.

Book XII. treats of conic sections and their principal solids: such figures only are inserted as are met with in practice for further information the pupil is desired to consult Emerson's and Simpson's Conic Sections.

Book XIII. treats of gauging, or the art of measuring such vessels as are used by maltsters, brewers, wine merchants, victuallers, and distillers, namely cisterns, couches, coppers, coolers, tuns, vats, and casks; to which are added the use and description of the sliding rule. If the pupil well understands mensuration of superficies and of solids, he will find little difficulty in measuring any vessel he may meet with, as mensuration of superficies and of solids is the ground work of all practical mensuration.

Book XIV. treats of plane trigonometry, logarithms, heights and distances, railway surveying, descriptions of the theodolite and circumferentor. Various writers on land-surveying have introduced these instruments in measuring estates, but the method by the chain alone is far preferable; the chief use of these instruments being in measuring roads, rivers, large towns, and county surveying.

Book XV. contains the whole art of levelling and drawing the plan or section, with descriptions of the instruments used therein.

Having given the principal design and object of this work, let me solicit the attention of the reader in the study of it, so that it may tend to his advantage. The general way among learners in going through books of mensuration, &c., is scarcely ever to commit the rules to memory, so as to be able to solve any particular question they may meet with in practice, without the assistance of a book. But if the pupil wishes to study this work to his profit, he should commit the different rules to memory, and carefully study them in his mind till they are thoroughly understood by him. By so doing, the principles of mensuration will be readily comprehended, and the pupil, by close application, will be enabled to reduce theory into practice with pleasure to himself, and satisfaction to his employers. If this shall be the result of his labour, the author will be doubly gratified; first, in the improvement of his own practice by this close study of the subject; and lastly, in the satisfaction of being useful to the rising generation.

York, May 22, 1838.

THOS. HOLLIDAY.

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