THE YOUNG SCIENTIST. 
47 
and slid from one end to the other of the 
saw. Now this is the simplest of ways to 
flle a saw, but it is very seldom success- 
ful, from the fact that it is almost impos- 
sible to follow the lines of angles first 
made in the saw without making soine 
teeth smaller than others, and again, it is 
nnscieutific, and therefore unsound. Con- 
sequently, it is much better to learn how 
to flle a saw on correct principles. 
Three kinds of teeth are used on hand- 
saws for cross-cutting; one for cutting 
very soft wood, such as pine, whitewood, 
bass wood, butternut and chestnut. This 
kind of a tooth, enlarged, is shown at 
Fig. D. 
sliapes may be slightly varied to suit con- 
ditious, but the i)rijiciples involved will 
always remain the same. 
Fig. D. 
I do not advise the use of t his tooth for 
the amateur, for many reasons, among 
which may be meotioued the difficulty of 
keeping it in order, its liability to break 
and otherwise get dull, and its unfitness 
for use on hard woods. 
Fig. E shows teeth that are adapted for 
Fig. E. 
either hard or soft wood, and are the 
teeth the amateur should always adopt, 
as they will work with tolerable ease in 
either case. 
Fig. F shows three teeth adapted par- 
ticularly for hard woods. It will be no- 
ticed that these teeth have wide bases 
and are more obtuse than the teeth shown 
in the two previous examples. These 
three examples of teeth show all that the 
amateur will care to know of sawteeth 
suitable for cutting across the fibres of 
wood, hard or soft. Of course, these 
Fig. F. 
Portions of saws, showing the teeth 
about the right size for working, are here- 
with illustrated, giving the reader an idea 
of what the saw should be. 
Fig. G shows the teeth for soft wood, 
the same as 
shown at 
Fig. D. Fig. 
H shows the 
teeth suita- 
ble for either 
hard or soft 
woods. 
This is the style of tooth I 
for amateur 
use. It will 
not cut so 
rapidly as 
the teeth 
shown in 
Fig. G, but it 
will give bet- 
ter satisfaction all round. 
Fig. K. 
Fig. K shows the teeth best adapted for 
cutting hard wood, and it shows the teeth 
about the size they should be for an ordi- 
nary hand-saw. 
So far I have only dealt with hand-saws 
for cross-cutting ; in subsequent issues of 
the Young Scientist I will have some- 
thing to say on ripping-saws, which re- 
quire a different mode of treatment than 
those I have mentioned. The several 
