Am.  Jour.  Pharm  ) 
April,  1879.  J 
Present  to  Our  Youngsters. 
163 
A  SENSIBLE  PRESENT  TO  OUR  YOUNGSTERS. 
By  Hans  M.  Wilder. 
The  Orange  Judd  Co.  ("American  Agriculturist"),  245  Broad- 
way, New  York,  have  just  got  out  a  ten  dollar  microscope,  and  a 
splendid  instrument  it  is  for  the  price.  This  has  only  been  made  pos- 
sible by  manufacturing  it  by  the  thousands. 
Like  most  of  the  optical  instruments  of  the  Bausch  &  Lomb  Co., 
Rochester,  N.  Y.,  it  has  hard  rubber  substituted  for  brass  wherever 
possible  ;  the  few  parts  that  have  to  be  made  of  brass  are  nickel  plated, 
and  it  thus  forms — black  relieved  by  white,  and  of  gracious  design — a 
beautiful  little  instrument.  Its  magnifying  power  is  about  up  to  one 
hundred  diameters  ;  it  has  a  divided  objective,  which — although  not 
claimed  to  be  achromatic — shows  no  more  color  than  the  ordinary  run 
of  so-called  "achromatic"  French  objectives.  Its  concave  mirror, 
besides  the  ordinary  double  motion,  can  be  turned  up  over  the  stage 
and  serve  as  condenser.  This  little  microscope  has  one  feature  hith- 
erto only  found  in  fifty  dollar  (and  higher)  instruments,  viz.,  a  camera 
lucida  of  very  simple  construction.  It  is  very  easy  to  draw  by  means 
of  it.  It  has  a  draw-tube,  and  is  moved  by  rack  (two  large  milled 
heads).  Considering  its  low  price  and  low  magnifying  power,  it  will 
probably  be  questioned  whether  it  is  good  enough  for  anything  but  a 
scientific  toy. 
Little  as  it  magnifies,  and  although  its  objectives  are  not  professedly 
achromatic,  it  enables  us  to  follow  nearly  all  the  descriptions  and  expla- 
nations found  in  our  text-books.  It  serves  to  familiarize  our  appren- 
tices with  the  handling  a,nd  working  of  a  microscope,  not  to  mention 
that  much  time  otherwise  thrown  away  in  frivolous  pursuit  will  be 
spent  profitably. 
I  think  that  such  an  instrument  would  be  a  sensible  present  to  make 
to  our  deserving  apprentices  ;  the  money  cannot  well  be  spent  better. 
Since  beginners  in  microscopy  are  generally  inclined  to  use  too  large 
amplifications,  it  will  not  be  out  of  place  to  mention  that  the  diameter 
of  the  field  seen  with  a  magnifying  power  of  25  diameters  is  about  a 
quarter  of  an  inch  ;  with  50  diameters  about  one-eighth  of  an  inch  ; 
with  100  diameters  about  one-sixteenth  of  an  inch,  and  so  on.  The 
head  of  a  fly,  for  instance,  is  about  one-eighth  of  an  inch  broad,  and 
will  about  cover  the  whole  field  of  an  amplification  of  50  diameters. 
