1 88 2.] Scientific News. 347 



Bausch's Homogeneous Immersion Objectives. — The Bausch 

 & Lomb Optical Company, Rochester, which, under the able su- 

 pervision of Mr. Edward Bausch, is making remarkable progress 

 in the construction of lenses, has added to its list a series of hom- 

 ogeneous immersion objectives, from -}th to ^Vth inch, claiming 

 an angular aperture of 140 in medium equivalent to crown glass. 

 They are made adjustable, and up to T Vth inch cost from $70 to 

 $100. By a change of adjustment they are capable of use as 



genious construction is made for use with them. New J^th, dry, 

 of 140 is also made, with long working focus, and so well cor- 

 rected that it will resolve No. 18 or No. 19 of Moller's test-plate 

 in balsam. 



Lehigh Valley Microscopical Society. — This new society 

 held its February meeting in Easton, with a good attendance. 

 Dr. Isaac Ott described and illustrated Dr. Stohrer's (of Leipsic) 

 plan for registering the growth of plants, and confirmed that au- 

 thor's hypothesis that during the day plants do not grow as rap- 

 idly as at night. Mr. F. Wolle exhibited specimens of filamentous 

 alga, illustrating a growth in some instances of from one-half to 

 three-quarters of an inch per hour. Mr. E. A. Rau also exhibited 

 botanical specimens illustrating the growth of the lower orders. 

 Other objects were shown by E. P. Seip and Breinig, and Mr. G. 

 W. Stout. 



Pigeon-post Films. — Having obtained a supply of the gelatine 

 films used for transmission of news by pigeon-post during the 

 siege of Paris (the expedient of posting desp itches in the form of 

 microscopic photographs, by the way, having been suggested by 

 Sir David Brewster nearly fifty years ago), the editor of this de- 

 partment of the Naturalist will take pleasure in sending .an un- 

 mounted specimen, sufficient for a microscopic object, to any per- 

 son sending him a stamped and directed envelope for that pur- 

 pose. Return exchange optional. 



Blood Stains on Steel.— Dr. M. C. White, of New Haven, 

 has been able to recognize and measure, by means of the vertical 

 illuminator and a eighth objective, blood-corpuscles upon a steel 

 instrument that had been exposed during two winters in the 



SCIENTIFIC NEWS. 



report of the Boston Society of Natural History 

 •cording progress in the arrangement of the mu- 



>y the citizens at large in the popular work of tli£ 

 fusion of science. Two ladies have generously 

 penses of the Teachers' School of Science estab- 



