and Laboratory Methods. 1445 



accessory apparatus, illuminant, etc., used, are interesting as showing advance 

 made by American opticians in constructive optical mathematics and the possi- 

 bilities of the application of theoretical conclusions in the production of an 

 apochromatic objective system, without the use of other materials than the 

 glasses ordinarily employed : 



" Although I cannot claim any expert knowledge of optical science, my exper- 

 ience during the past six years in difficult photo-micrography may make my test 

 of this glass in the camera of some worth to you. I find it superior in working 

 quality to any lens of apochromatic focus I have yet tried except the Zeiss 

 apochromatic of 4 mm., and as to that it holds its own for photographing. The 

 correction for actinic rays is surprisingly good, so that exquisite definition is 

 obtainable, even with a projection ocular No. 4, and it does not bring it 

 down under a compensation ocular No. 8. Notwithstanding the extremely 

 wide aperture, the field is perfectly flat, so that perfect photographic defini- 

 tion is obtained to the edges of a large circle on the focusing screen. It 

 bears more light than any others I have tried, and I can open the condenser 

 and diaphragm at least 40 per cent, more than with the other glasses, and still 

 get excellent photographic contrast. 



" The focus of this lens appears to be a trifle less than 5 mm., about 4.65 mm., 

 as nearly as I can estimate it by comparison of the negatives with it, and the 

 Zeiss 4 mm." l, b. e. 



The New Medical Laboratories of the University of 



Pennsylvania. 



The University of Pennsylvania is about to erect, at a cost of more than 

 ,000, exclusive of grounds and equipment, a Medical Laboratory building 

 which will be unexcelled in every respect. The trustees are also contemplating 

 the erection in the near future of a new Medical Hall, Anatomical Building, and 

 auxiliary buildings, which will adjoin the new laboratory about to be erected, 

 and which will form one of the most extensive systems of buildings devoted 

 exclusively to the teaching of medicine in Europe or America. 



The new Medical Laboratory building, which will be erected at once, will be 

 quadrangular in shape, and will be located on the south side of Hamilton walk, 

 between Thirty-sixth and Thirty-seventh streets. The building will be two 

 stories in height above a high basement, and measure 340 feet front by nearly 

 200 feet in depth. The long front faces north, securing a maximum amount of 

 the best light for laboratory purposes. All along the front are arranged small 

 rooms for research, rooms for professors and their assistants, a library, etc. ; 

 these open into a private corridor, so that men employed in these rooms may 

 pursue their work without interruption from students passing through the main 

 halls. 



Perfect lighting of all the laboratories has been obtained, the courts being 

 large enough, with the low front building, to furnish good north light to the 



