1895 THE MICROSCOPE. 3 



is of the greatest importance. If the stage does not 

 move easily, remove the parts from the rod and wipe 

 the rod with an oily cloth, being very careful not to soil 

 any of the parts, especially the glass. If any thing 

 should soil the lenses wipe them with a clean, soft linen 

 handkerchief, kept especially for the purpose, for a 

 scratch on the lens would mean a line across every 

 object seen through it ever after. There is one difficulty 

 with this little instrument, — it is so light that it moves 

 easily and disarranges the object. To obviate this 

 take a piece of smooth board four inches by six and 

 an inch thick and with one little screw fasten the 

 case to the center of the board. This will make it 

 quite firm. As the fly is an opaque object, if your light 

 is strong sun-light, you can use the dark background 

 which should then be turned so as to hide the mirror but 

 better results can be gotten with the mirror turned 

 so as to show a light field but not a bright one. The 

 fly will be magnified about thirteen diameters. We 

 will first learn the position of each of the parts, sep- 

 arately. 



The redish brown spots on either side of the head 

 (Fig. 1, E) are the eyes. Between the eyes the head is 

 covered with short yellowish and black hairs and just 

 at the front of the head are what look like two tufts 

 or long black hairs. These are the antennae (Fig. 1 A). 

 The head is joined to the body or thorax, by a very 

 short neck, and, if you watch a fly, you will see that 

 he seems to have the power to turn his head quite 

 around. The thorax is covered with the yellowish and 

 black hairs in stripes, and to this are attached three 

 pairs of legs, two wings and the abdomen. 



I^ow move the stage up a very little so as to bring 

 the legs into focus. These consist of several joints. 

 There is one which joins the body and that we do 

 not see called the eorca, next comes the femur or thigh, 



