| No. 83. | Screw-micrometer eye-piece for accurate measurement of
large objects. Between the eye lens and the collecting
lens of a Huyghenian ocular there is a millimeter scale
etched on glass, above which is a moveable indicator
whose position is controlled by a micrometer screw to
which a graduated drum is attached. The value of each
graduation on the drum (about 1/20 of the micrometer
value of the objective) must be determined for each
combination of ocular and objective by means of the
stage micrometer. The eye lens of the ocular is moveable
to permit accurate focus upon the scale. The apparatus
slips into the tube of the microscope like any ordinary eye-piece
and is fixed in position by a thumb-screw at the side | $20.— |
| No. 84. | Micrometer eye-piece. The mount unscrews in the centre to
permit the introduction of the micrometer scale. The eye
lens is moveable to permit of accurate focus on the scale | $4.— |
| No. 85. | Glass-Micrometer for the eye-piece, to drop on the diaphragm
of the eye-piece. Scale of 5 mm divided into 100 parts | $2.50 |
| No. 86. | The same, 10 mm divided into 100 parts | $2.— |
| No. 87. | Stage-Micrometer, 1 mm divided into 100 parts etched on glass | $3.75 |
| No. 88. | Stage-Micrometer, photographed on glass, 2 mm divided into 200 parts | $1.40 |
| No. 89. | Eye-piece Micrometer, divided into squares for counting
scattered objects in the field. Mounted. Distance between the lines 0,5 mm | $2.— |
| No. 90. | Glass slide with cell 2/10 mm deep, with ocular micrometer
No. 89, in box | $3.25 |
| No. 91. | Glass slide with cell the floor of which is divided into
squares, 1/400 square mm each, in box | $4.— |
