[     368     ] 
XI/VI.   On  a  Collector  for  Frictional  Electrical  Machines. 
By  Dr.  H.  Emsmann*. 
FROM  observing  how  effective  the  condenser  is  when  applied 
to  Ruhmkorff's  coil,  notwithstanding  the  small  space  that 
it  occupies,  I  was  led  to  imagine  that  a  compendious  collector, 
which  would  nevertheless  increase  the  effect  considerably,  might, 
in  like  manner,  be  adapted  to  the  ordinary  frictional  electrical 
machine. 
In  this  I  have  been  completely  successful.  At  an  inconsider- 
able outlay  I  have  attained  what  the  remarkable  and  compa- 
ratively expensive  ring  (now,  however,  disproportionately  expen- 
sive) produces  when  adapted  to  Winter's  electrical  machine. 
My  original  idea  was  to  form  the  collector  of  a  single  long 
strip  of  tinfoil  to  be  folded  up  between  two  overlapping  strips  of 
waxed  paper,  and  which  would  be  enclosed  in  a  cover  of  similar 
material  of  about  octavo  size.  I  purposed  placing  this  collector 
on  the  conductor  itself  of  the  machine  (like  Winter's  ring),  or  on 
the  metallic  portion  between  the  conductor  and  the  points. 
M.  Kuhlo,  the  assiduous  and  skilful  philosophical-instrument- 
maker  of  this  place,  to  whom  I  addressed  myself  to  carry  out 
my  idea,  has  now  executed  the  collector  in  this  way — namely,  by 
inserting  into  each  other  several  glass  tubes  hermetically  sealed 
at  one  end,  the  diameter  of  the  widest  tube  being  about  2  inches. 
With  the  exception  of  the  widest,  which  serves  simply  as  an 
insulating  cover,  all  the  tubes,  varying 'in  number  from  three  to 
five,  are  coated  externally  with  tinfoil  applied  with  paste ;  the 
edges  of  their  open  ends  lie  in  the  same  plane;  and  at  those  ends 
all  these  tinfoil  coatings  are  united  together  and  brought  into 
metallic  connexion  with  the  conductor  of  the  machine,  the  ar- 
rangement being  such  that  the  collector  can  be  adapted  thereto 
or  removed  at  pleasure. 
The  effect  produced  is  astonishing.  The  collector  accom- 
plishes even  more  than  Winter's  ring  does  when  placed,  instead 
thereof,  upon  a  machine  furnished  with  such  a  ring. 
This  simple  and  inexpensive  collector  can  be  easily  adapted  to 
any  frictional  electrical  machine;  so  that  with  every  such  machine 
we  may  obtain  in  an  easy  and  cheap  manner  similar  effects  to 
those  for  which  Winter's  ring  was  so  remarkable. 
Stettin,  February  1872. 
*  Communicated  by  W.  G.  Lettsom,  Esq.,  from  PoggendorfFs  Annalen, 
vol.  cxlv.  p.  332. 
