17. _Forts, Redoubts._—Remark their form, whether ancient or modern; whether they are permanent or temporary; elevated or low; revetted or demi-revetted, with stone, brick, or turf. Whether the ditch is wet or dry; fraized or palissaded; natural or artificial. Observe their situation; the face of the adjacent country; whether they effectually command the passes, or protect the country intended. The defence they are capable of making in their present state, and the improvements of which they are susceptible. 18. _Castles, Citadels._—Their situation; their form; their extent; their object; the protection they give the city; their connection and communication with it. The present state of their defence, and the improvements of which they are susceptible. Their _Souterraines_. 19. _Villages._—Observe their situation; ascertain the number of families they contain; the nature of the land; the quality and quantity of their crops; their markets; the suburbs that supply these markets; their beasts of burthen: their flocks, herds, poultry, _&c._ The number of their ovens; quality of the water; stile of houses, barns, stables, and sheep walks. The situation of the church; the nature of the church yard, and its enclosures. The wind and water mills. Observe whether the village is surrounded by hedges, ditches, banks, or walls; whether it can be easily intrenched. Its streets; roads leading to it; and the face of the surrounding country. 20. _Cities not fortified._—Their situation; population; commerce; commodities; manufactures; the succours that may be drawn from them, as to men, horses, _&c._ Their squares and principal buildings. The defence they are susceptible of; whether they are surrounded by walls, old towers, ditches, _&c._ Their gates, and the roads leading to them. The face of the surrounding country. 21. _Fortified Towns._—Their situation with respect to their position, and with respect to other towns in the neighbourhood, whether in the first or second line; the assistance which they can afford each other. The succours that may be drawn from them, or that may be thrown into them in case of a siege. The direction which such relief, whether of men or provisions, ought to take, according to the side attacked; whether they will serve as depots or hospitals. The state of the fortifications (see the word _Fortification_ in the alphabet;) their nature; the strength of each front. The rivers in the neighbourhood; the surrounding country within the range of the guns. The form of investment; what lines will be required considering the nature of the country, and the positions; and the means the country affords of executing them. The advantages which the ground would afford between the glacis and the lines, either to the besiegers or besieged; the means of establishing the most certain communications between the different quarters of the army, and the means of cutting them off.