irrecoverably, and occasions a very considerable expense. The javeline and arrows which were thrown or shot in an ancient one could easily be picked up again, and were besides of very little value. The cannon and the mortar are not only much dearer, but much heavier machines than the balista or catapulta, and require a greater expense, not only to prepare them for the field, but to carry them to it. As the superiority of the modern artillery too over that of the ancients is very great, it has become much more difficult, and consequently much more expensive, to fortify a town so as to resist even for a few weeks the attack of that superior artillery.

In modern times many different causes contribute to render the defence of the society more expensive. The unavoidable effects of the natural progress of improvement have, in