A HOME-MADE TELESCOPE. 85 



growth of truth, which you call scientific truth ? If these beliefs are 

 destroyed, is it not a conclusive proof that they may be false, or at 

 least contain an element of untruth ? The religion may, indeed, have 

 been very useful, although not true, and not qualified to satisfy all the 

 aspirations of a cultivated mind. You may see, when a civilized race 

 comes in contact with a lower race, that the effect of the sudden con- 

 tact may be to destroy the religion and the rule of life of the inferior 

 race, without putting anything in its place. Evils of that kind have 

 been caused by modern science. It is destroying inevitably many be- 

 liefs which people have lived under well and happily. It is undeniable 

 that this causes pain, and that it may be injurious to their morality I 

 shall not attempt to deny. But when I am asked to say that therefore 

 science is injurious, I have to come back to my original proposition 

 the remedy is more science. The only way out of the difficulty is 

 this : we are here, and we have got to go forward. And the only 

 way is, to apply the test of truth to all our beliefs. This effects a cer- 

 tain amount of pain, as every other kind of progress does ; but the 

 only other way is to go on believing what you know to be lies. And, 

 without saying which are true and which are false, I can not see who 

 any person can wish to do anything else but increase the amount of 

 truth, the only satisfactory cure." Knowledge. 



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A HOME-MADE TELESCOPE. 



By Dr. GEORGE PYBUEN. 



TO render easier of attainment instruments which assist in the in- 

 vestigation or contemplation of natural phenomena, and which 

 supplement man's sense-organs, is to forward by so much the diffusion 

 of real knowledge, and to aid the work of human enlightenment and 

 progress. Indeed, it is not to be doubted that the popularizing of 

 instrumental aids for experimentally verifying the teachings of scien- 

 tific discoverers will form a notable part of the work of the future 

 schoolmaster. 



A few years ago I derived great pleasure from successfully con- 

 structing a home-made microscope, guided by directions contained in 

 " The Popular Science Monthly," at a time when my means did not 

 enable me to purchase a good instrument from the optician. I now 

 lay before my fellow-readers the following directions which, step by 

 step, I myself have put in practice, in making a really serviceable 

 achromatic telescope, which will exhibit the moon's surface magnifi- 

 cently, and show very satisfactorily the spots on the sun's disk, the 

 satellites of Jupiter, and other celestial phenomena. 



Some people conclude that, if they can not possess a first-class in- 



