Complete, with support. Each $8.50

15380. Glass parts only, for No. 15378. Each $5.50

Lenses, Demonstration. These lenses show the forms of the various
elementary lenses and demonstrate their optical principles. The
edges are ground smooth, and polished.
15382. Lenses, Demonstration. Set of six lenses, viz. : double convex, double
concave, piano convex, piano concave, meniscus convex, and men-
iscus concave; in box.
Diameter of lenses, mm. 37 50 75



Per set



1.25



2.50



4-5°



15384. Lenses, Demonstration. Set of ten lenses, viz.: double convex,
double concave, piano convex, piano concave, meniscus convex,
meniscus concave, cylindrical convex, cylindrical concave, sphero-
cylindrical, and prismatic.
Diameter of lenses, mm. zj 50 75



Per set 2.00

Lenses, Double Convex or concave.
Ground Edges



3-50



7-50



Perfectly Centered



Catalog.
Diam.
Focus




Catalog.
Diam.
Focus




Number


mm.
mm.
Each


Number


mm.
mm.
Each


15386


1-5


3


$0.75


15412


1-5


3


$1.00


15388


3


6


•75


15414


3


6


1. 00


15390


5


10


•75


1 541 6


5


10


1. 00


15392


6


13


.go


15418


6


13


1. 00


15394


10


19


.90


15420


10


19


1. 00


15396


13


25


■90


15422


13


25


1. 00


15398


16


32


.90


15424


16


32


1-25


15400


19


38


.90


15426


19


38


1.25


15402


25


51


.go


15428


25


SI


1^25


15404


38


76


.50


15430


38


76


•8s


15406


50


102


.60


15432


SO


102


•95


15408


62


127


•75


1 5434


62


127


1^25


15410


75


152


I^25


15436


75


152


1^75



New York, Boston, Chicago, U. S. A., Frankfurt a/M., Germany.
283



1 5550.
15552-



Lenses, Double Convex or Concave — Large Diameter.
mm. cms. Each mm. cms.
