264 ORDINARY MICROSCOPE FOR PROJECTION [Cn. IX 



As here shown the substage condenser and mirror have been removed, and 

 also the draw-tube and ocular (see fig. 147, 192 for the ordinary microscope 

 with substage condenser, draw-tube and ocular in position). 



The lamp, condenser and microscope are on independent blocks and can be 

 moved to any desired position on the baseboard. 



A The ammeter to indicate the amount of current. 



R Adjustable rheostat. This rheostat is adjustable between 10 and 20 

 amperes. The arrow indicates the direction of increase in current. 



5 Adjustable drawing shelf attached to the front legs of the table. In this 

 picture the shelf supports the stage of the projection microscope (fig. 121), and 

 a box of demonstration specimens. 



The scale of the picture is indicated by the 10 cm. rule just above the table 

 drawer at the right. 



If the tube of the microscope is large it is an advantage, but with 

 the small tube one can do much. If the ocular is not to be used, 

 then it is better to remove the draw-tube so that only the main 

 tube remains. One should be sure that the interior of the tube is 

 dull black ( 370). 



394. Magic lantern with rods, and an ordinary microscope. 



If the magic lantern has the simple construction with rods and feet 

 (fig. 32, 33, 36) an ordinary microscope can be used with it as 

 follows: Remove the rods, bellows and projection objective, and 

 support the arc lamp and the condenser on a block which will lift 

 them high enough so that the microscope in a horizontal position 

 will be in the optic axis. Place all on a baseboard with guides 

 (fig. 146). Clamp the microscope to a suitable block with grooves 

 or cleats to enable one to move the block accurately along the 

 guides. When properly centered this form of apparatus w^orks 

 well. 



394a. For a water-cell one of the plane-sided glass boxes found on the 

 market can be used, or a cell can be prepared in the laboratory as follows: 

 Select some good plane and clear glass. For the ends of the box make two 

 strips about 2^2 cm. (i in.) wide and about 10 cm. (4 in.) long. For the sides 

 use two sheets about 10 cm. (4 in.) wide and II cm. (4^2 in.) long; and for 

 the bottom a rather thick sheet or strip about u cm. (4^2 in.) long and 3 cm. 

 (i '4 in.) wide. The pieces of glass are then put together by placing the bottom 

 on a level table and the other pieces in position and held in place by a string 

 or by narrow strips of gummed paper. 



The joints are then gone over carefully with an artist's brush dipped in 

 Ripolin white paint or Valspar varnish. Each coat should be allowed to dry 

 thoroughly before adding the next, that is, for two to five days. Finally one 

 can add water to see if the joints are all tight. It" not, dry the glass box am', 

 then add more of the Ripolin paint or Valspar varnish. 



