ni 



POCKET MAGNIFIERS 



No. 30980 



No. 30984 



30988 



30976. Magnifiers, Doublets, Bausch & Lomb, with nickel metal mounting. Consisting 

 of two separated plano-convex lenses ground and polished to give satisfactory re- 

 sults for medium power magnifications. No. 136 is a hand magnifier with hexagonal 

 handle and No. 137 has folding pocket case. 



Number 136 137 



Magnification lOX lOX 



Each .75 $1.00 



30980. Magnifiers, Coddington, Bausch & Lomb, giving a good definition and wide field. 

 They are composed of a cylinder of glass with a deep groove cut in at an equal dis- 

 tance from the ends to serve as a diaphragm. The ends of this cylinder are ground 

 spherically and polished to form the lens surfaces. 

 Magnification 20X 15X lOX 5X 



Each $1.50 $1.50 $1.50 $1.50 



30984. Magnifiers, Triple Aplanats, Bausch & Lomb, composed of two meniscus lenses of 

 flint glass, separated by a double convex lens of crown glass. The field of these 

 magnifiers is large and has a perfect correction for chromatic aberration as well as 

 for flatness, astigmatism and distortion. Their working distance is little short of a 

 simple lens of the same equivalent focal length. 

 Magnification 20X 15X lOX 8X 



Each $3.50 $3.50 $3.50 $3.50 



30988. Magnifiers, Hastings Aplanatic Triplet, Bausch & Lomb, made after formulae 

 by Prof. C. S. Hastings, of Sheffield Scientific School, Yale University. These are 

 among the most perfect magnifiers produced. The angle of view embraced is very 

 large and the working distance almost equal to that of a single lens.of the same focus. 

 Magnification 20X 15X lOX 7X 



Each $7.50 $7.50 $7.50 $7.50 



Any of the above Magnifiers will be sent by parcel past upDa reseipt of price- 

 Special discount to educational institutions. 



ARTHUR H. THOMAS COMPANY 



IMPORTERS — DEALERS — EXPORTERS 



LABORATORY APPARATUS AND REAGENTS 



WEST WASHINGTON SQUARE PHILADELPHIA, U. S. A. 



Please mention the Journal of Economic Entomology when writing to advertisers. 



