As the work of the compass saw, illustrated in Fig. 20, will be both with and across the grain of the wood, the best form of tooth will be that shown in Fig. 21, having more pitch, and slightly less bevel, than the crosscut saw. A crosscut saw will rip better than a rip saw will crosscut; hence the shape of tooth should be between the two. Compass saws are ground very thin on the back of the blade, but in order to turn easily they should be set the same as hand saws. And here wo wish to impress on the beginner the necessity of keeping his saw- and indeed all other cutting tools - perfectly sharp and in good working condition at all times. A sharp saw will work faster, and will always do smoother and better work with less set and with less expenditure of power, than a dull one. Even to saw well is an art, which cannot be gained through the use of dull, imperfectly set, and poorly kept tools. To file well will require from the beginner close attention, a study of the subject, and careful practice, all of which can be given by any one possessing ordinary mechanical ability. If the filing is done slowly at first, care being taken to hold the file at the same angle for all the teeth, a little faithful practice will always bring success.