The Stage 15 



vertical direction. If properly fitted and sprung, it will 

 travel freely when gently pressed with one hand only. The 

 object is carried by it, and can be moved in a horizontal 

 direction upon this bar. With a little practice the fingers 

 become educated to the work, enabling examinations to be 

 conducted with the highest powers almost as rapidly and 

 systematically as with the mechanical screws. This sliding- 

 bar should further be provided with two flat springs, so 

 fitted that they may be turned inwards to rest on the bar 

 when not required. It is often necessary to set an object 

 at an angle across the stage during observation, in order 

 that some special feature may appear vertically in the 

 centre of the field: If the springs be not provided this 

 cannot be done. 



Finders foe Plain Stages. — The form of finder sug- 

 gested by Mr. Lewis Wright for plain stages is the most 

 efScient for practical purposes. Many proposals have been 

 made, but none equal this one for simplicity. On the right- 

 hand side of the central aperture, one inch of the stage is 

 divided into 50 parts in vertical and horizontal directions. 

 A special feature of interest in an object having been dis- 

 covered, the slide being maintained in a horizontal position 

 across the stage by means of the sliding-bar, it is only 

 necessary to read from the top right-hand corner of the 

 slide the lines against which it lies. A note of same is 

 made on the labels of the object, and the specimen can sub- 

 sequently be placed in exactly the same position, and the 

 subject re-examined. Without the sliding-bar it is some- 

 what difficult to keep the object exactly straight across the 

 stage, but with care, on observing an important feature, the 

 slide can be gently turned until it is in a correct position 

 for taking readings. 



The great saving of time that is afforded by such a device 

 as this should establish its claim to be placed on every 

 student's microscope. Several makers have already adopted 

 the arrangement, and it would be a great gain to micro- 

 scopists in general if a uniform position for the divisions 



