THERMOGRAPHS 



kjUUEN 



P.FRIEZ. BELFORT n^/^OgSERVATQRY. BALTIMORE 



HYGROGRAPHS 



JU UEN P.FRrEZ.BELFORT T;;^0B5ERVAT0RY.BALTIM0 RE.MD.I 



COMBINED THERMO-HYGROGRAPHS 



'Write for prices to 

 JULIEN P. FRIEZ, Belfort Observatory, BALTIMORE, MD. 



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



