560  United  States  Army  Laboratory.  {ASeCl™be*ml?' 
an  opening  for  me  in  the  Army  Laboratory  that  was  about  to  be 
established  in  Philadelphia,  and,  thanks  to  the  Messrs.  Wyeth  and 
to  Prof.  John  M.  Maisch,  whose  acquaintance  I  had  made  under 
favorable  auspices,  I  succeeded  in  obtaining  the  appointment  of 
Assistant  Chemist  under  Professor  Maisch. 
More  than  forty  years  have  elapsed  since  I  entered  upon  my  duties 
in  the  United  States  Army  Laboratory  at  the  N.  E.  corner  Sixth 
and  Oxford  Streets,  Philadelphia  (during  April,  1863),  and  I  depend 
altogether  on  memory,  with  the  slender  reminder  of  several 
photographic  interiors,  for  what  I  am  about  to  say.  The  grounds 
on  which  the  laboratory  was  situated  occupied  a  parallelogram  of,  I 
should  say,  about  150  to  175  feet.  The  main  building,  three  stories 
high,  with  a  well-lighted  basement  throughout,  faced  west  on  Sixth 
Street,  flush  with  the  pavement,  about  100  feet  long  and  joining  a 
one-story  building  on  Oxford  Street,  facing  south,  about  60  or  pos- 
sibly 75  feet  long,  and  perhaps  60  feet  in  depth,  while  on  Sixth 
Street,  or  the  main  front,  it  was  separated  by  a  gateway  from 
another  one-storied  structure,  extending  eastward  about  85  to  100 
feet  and  constituting  the  northern  boundary  of  the  grounds.  The 
remaining  portions  of  the  northern  and  southern  boundaries  were 
enclosed  by  a  wooden  fence,  as  was  also  the  rear,  or  eastern  boundary, 
when  the  laboratory  was  first  opened,  but  in  time  was  occupied  by 
a  frame  structure,  running  the  entire  length,  and  used  for  the  wash- 
ing and  storage  of  bottles,  the  carpenter-shop  and  other  similar 
purposes.  The  only  entrance  into  the  laboratory  from  the  street 
was  an  ordinary  doorway,  immediately  adjacent  to  the  gateway 
mentioned,  which  was  for  the  exclusive  use  of  teams.  The  doorway 
opened  into  a  short,  rather  narrow  passage,  to  the  left  of  which  was 
a  small  office,  and  immediately  adjoining  this  the  private  office  of 
the  Superintendent,  Surgeon  A.  K.  Smith,  and  of  the  Chief 
Chemist,  Professor  Maisch,  who,  however,  used  it  chiefly  as  an  experi- 
mental laboratory.  Through  the  T-<ort  passage  mentioned,  leading 
into  the  packing  room,  the  employee  ^d  to  pass  on  their  way  to 
and  from  their  work,  and  consequently  under  surveillance  from  the 
office — those  employed  on  the  upper  floor  of  the  main  building 
reaching  their  stations  by  a  single  (and  only)  stairway  along  the 
east  wall  of  the  packing-rooms — the  latter  occupying  about  one-half 
the  space  of  the  first  floor,  minus  the  space  occupied  by  the  offices 
and  hallway.    The  remaining  half  of  the  first  floor — composing  the 
