Scie7itific Intelligence. — Statistics. 395 



lately completed two, one of 6 inches, and the other of 3| aper- 

 ture, which, as experimental results, are very satisfactory. The 

 principle of the construction, which is Professor Barlow's, pos- 

 sesses some novelty, and some important advantages, one of the 

 most valuable being, that the telescope may be made considera- 

 bly shorter than in the usual refractors, without a correspond- 

 ing diminution of the focal powers, the focal length being near- 

 ly double the length of the tube, as in the Gregorian reflector. 

 We are assured tliat, with the small telescope, Avith a power of 

 only 46^ polaris is distinctly doubled, and the small stars well 

 defined ; and with higher powers, all the double stars of Sir 

 William HerschePs third class are distincdy separated, and se- 

 veral of the second class ; the larger telescope has not at present 

 been submitted to so severe a test, but neither the maker, nor 

 the projector, has any doubt of its answering equally well, and be- 

 ing proportionally more powerful. Our correspondent, however, 

 informs us, that, in the larger telescope, in particular, a second- 

 ary spectrum is formed, from the irrationality of the original 

 spectra, which is very obvious on a Lyra and Arcturus, although 

 scarcely perceptible with less luminous stars; but this, it is ex- 

 pected, will be removed by the mixture of other fluids. We 

 hope, in our next number, to be able to explain more particular- 

 ly the nature of this novel construction, as well as to announce 

 the completion of one of much larger dimensions, as we under- 

 stand it to be the intention of the spirited and ingenious makers 

 to carry the construction to its utmost possible limits. We can 

 only say they have our best wishes. It is always gratifying to 

 see men of sound theoretical knowledge combining their efforts 

 with others of practical skill and ingenuity, because, fi'om such 

 combination of talent, we have every reason to expect valuable 

 results. In the present instance, these interesting experiments are 

 in excellent hands, and we cannot but look forward with confi- 

 dence to their ultimate success. 



STATISTICS. 



45. View of the Scientific and Literary State of different 

 parts of Italy. (Revue Encyclop. Jan. 1827.) — In this ac- 

 count of the State of Literature and Science in Italy, there is 

 more said of the former than of the latter ; nevertheless, it shews 



