Viewed through this microscope, a fly's wing appears as large as a
person's hand, held at arm's length, and has the general
appearance shown in Fig. 3. The mother of vinegar examined in the
same way is seen to be swarming with a mass of wriggling little
worms, and may possibly cause the observer to abstain from all
salads forever after. An innocent-looking drop of water, in which
hay has been soaking for several days, reveals hundreds of little
infusoria, darting across the field in every direction. These and
hundreds of other interesting objects may be observed in this
little instrument, which costs little or nothing to make.
** How to Make a Telegraph Key and Sounder [76]
The sounder, Fig. 1, is made from an old electric-bell magnet, D,
fastened to a wooden base. The lever, A, can be made of brass and
the armature, C, is made of iron. The pivot, E, is made from a
wire nail and is soldered to A. It should be filed to a point at
each end so as to move freely in the bearings, B, which are pieces
of hard wood. The spring, H, is fastened at each end by pins, bent
as shown, and should not be too strong or the magnet will be
unable to move the armature.
Pages:
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193