956 Tfaxsactioxs of the American Institute. 



The Reflecting PyrometePw. 

 The American Journal of Science and Arts, after noticing a 

 statement in PoggendorfF 's Annalen that Prof. J. Miiller had made 

 an application of Poggendorff 's mirror arrangement to the measure- 

 ment ©f the expansion of solids bj heat, says : " It is not a little 

 remarkable that neither Prof. Miiller nor the distinguished editor of 

 the Annalen should be aware of the fact that the above-mentioned 

 instrument is not new, either in principle or application. The 

 reflecting pyrometer was invented in 1826 by Mr. Saxton, now of 

 Washington, D. C, and used by him in adjusting the compensation 

 of a pendulum. It is, however, first mentioned in print in Prof. 

 Bache's reports on Weights and Measures for 1846 and 1848, and 

 fully figured in the report for 1856. It is referred to as having been 

 used to compare the measuring bars for the base lines, in the Coast 

 Survey Report for 184T, and again more particularly in that for 

 1854, in which the base measuring apparatus is described and 

 figured." 



New Blasting Powder. 

 Alfred Nobel, the engineer who first practically applied nitro-gly- 

 cerin to blasting purposes, has recently taken out a patent in Eng- 

 land for a new explosive compound. According to the inventor, a 

 mixture of nitrate of potash, soda, baryta or lead, with resin, sugar, 

 starch, or other bodies rich in car])on, cannot be employed for blast- 

 ing except under strong pressure ; but, if moistened with a small 

 quantity of nitro-glycerin, so that each grain is surrounded by a 

 layer of it, the mass will become explosive under ordinary circum- 

 stances. Nobel gives the following proportions for his new blasting 

 material : " Sixty-eight parts of nitrate of baryta, twelve parts of char- 

 coal, if possible, such as contains some hydrogen, and twenty parts 

 of nitro-glycerin ; or, seventy parts nitrate baryta, ten of resin and 

 twenty of nitro-glycerin. An addition of five to eight parts of sul- 

 phur enhances the eff'ect, but diminislies the safety. It is set on fire 

 by ordinaiy primers with fulminate of met'cury." 



jTiiE Speed of Birds. 



Si)allanza found that the swallow can fly at the rate of ninety-two 



miles an hour, and he computes the rapidity of the swift to be not 



less than 250 miles an hour. If it can move at this rate, even for a 



short distance, the swift must be ranked as the swiftest of birds. The 



