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THE POPULAR SCIENCE MONTHLY. 



But, when Harvard is ready to remove 

 Greek from the list of prescribed subjects, 

 I believe that many classical schools will be 

 found liberal enough to give pupils every 

 opportunity to replace its study with Ger- 

 man, mathematics, and science, taught by 

 men both competent and sincere. 



George F. Forbes, 

 Master in Roxbury Latin School. 

 Roxbuby, Mass., November 14, 18S8. 



THE HOME-MADE TELESCOPE. 

 Messrs. Editors : 



While reading the very useful article in 

 the November issue of the " Monthly," by 

 Dr. George Pyburn, on "A Home-made 

 Telescope," it occurred to me that my own 

 experience in that direction, not covered by 

 Dr. Pyburn's article, might prove acceptable 

 to some of your readers. In constructing 

 my telescope I made the tube of paper and 

 paste substantially as described by Dr. Py- 

 burn, finishing with shellac-varnish as a 

 protection against moisture. The three-inch 

 object-glass cost about twenty-five dollars, 

 which is nearly the total outlay for the in- 

 strument, as I use for eye-pieces those be- 

 longing to my microscope. As these range 

 from a two-inch to a four-inch, I get a fair 

 astronomical telescope with powers from 

 twentv-five to two hundred diameters, af- 

 fording satisfactory views of the more in- 

 teresting celestial objects. For viewing the 

 sun, a light box open on one side is at- 

 tached to the tube, containing a sheet of 

 white paper on which the image of the sun 

 is received at a distance of nine or ten inches 

 from the eye-piece. The stand is unskill- 

 fully constructed of wood, but, as the instru- 

 ment is supported at two points, it is steady. 

 It is of convenient height for an observer in 

 a sitting posture, the object-end of the tele- 

 scope being made to swing. When in use 

 the telescope is strapped in a kind of long 

 trough made by nailing two strips of boards 

 together. This support is bolted at the end 

 next the observer to an axle having a ver- 

 tical motion. It has a horizontal motion on 

 the bolt. The end of the support toward 

 the object is given a vertical motion from 

 horizontal to perpendicular by a lever run- 

 ning through a mortice in the stand, and 

 working on a pin in the mortice. A rod 

 jointed on the lower end of the lever is al- 

 ways in reach of the observer with which to 

 manipulate it. The top of the lever is fitted 

 with a long horizontal roller, on which a 

 roller placed under the telescope - support 

 rests at right angles. The rollers crossing 

 each other at right angles, smooth and 

 steady motion is had both vertically and 

 horizontally. Such a stand may be made in 

 a day. George W. Morehouse. 



Wayland, New Yoek, October 29, 1883. 



INSECTS AS CAEEIEES OF DISEASE. 

 Messrs. Editors : 



Although not prepared to accept en- 

 tirely the theory so ably presented by Dr. 

 King, in the September number of your 

 magazine, as to the mosquital origin of ma- 

 laria, I believe in the power of insects to 

 transmit and disseminate infectious diseases. 

 The active agency of mosquitoes and other 

 insects in the spread of yellow fever has 

 never been fully appreciated, and it is to be 

 hoped that the attention of the boards of 

 health in the localities liable to this terrible 

 scourge will be directed to this source of 

 danger, and that they will establish cordons 

 of fires as well as men around infected dis- 

 tricts. However, my object in writing this 

 is merely to add further testimony as to the 

 fact of insects carrying disease. 



The interior counties of the Southern 

 States are infested by a minute fly, a lit- 

 tle larger than the sand-fly of the coast, 

 but without the sting of the latter. They 

 are called gnats or black gnats, and are 

 exceedingly troublesome, from their habit 

 of flying into the ears and eyes of both 

 men and animals. They also gather upon 

 any running sore or abrasion of the skin, 

 and, though they do not bite or sting, they 

 are very irritating. When they get into 

 the eye they cause a very sharp pain, and, 

 though immediately killed by the secre- 

 tions, the eye feels the effects for some 

 hours after. It has been observed that 

 during the seasons when these gnats are 

 most plentiful the disease known as sore- 

 eyes is most common and severe. 



Not being a physician, I do not know 

 the name of the disease, but it is very con- 

 tagious, and usually affects an entire family 

 when once introduced into it. The lids of 

 the eye become irritated and swollen, and the 

 entire ball is red and inflamed. Some per- 

 sons have lost the sight of one or both eyes 

 from it, and its effects are felt for months 

 after recovery. The intimate relation ex- 

 isting between this disease and the gnats is 

 so well recognized that the negroes say it is 

 caused by the gnats laying their eggs in the 

 eye. This, of course, is improbable, but 

 points clearly to them as the real cause in 

 some way. I do not think the irritation 

 arising from their getting into the eye is 

 the origin of the trouble, because the dis- 

 ease does not always or even generally fol- 

 low as a matter of course ; but I do think 

 that the germs are carried upon the legs or 

 wings of the gnats, and that, when one so 

 charged touches or gets into the eye, the 

 germ or bacteria is deposited, and from that 

 the disease is developed. 



Of course, there are other ways of trans- 

 mitting the disease, but the most active 

 agent is undoubtedly the gnat, since after 

 it disappears the disease ceases to spread, 

 and gradually loses its character as an epi- 



