was　1500　tons。　　In　course　of　time　other　iron　works　were　erected；　at
  Clyde　Cleugh；　Muirkirk；　and　Devonthe　managers　and　overseers　of
  which；　as　well　as　the　workmen；　had　mostly　received　their　training　and
  experience　at　Carronuntil　at　length　the　iron　trade　of　Scotland　has
  assumed　such　a　magnitude　that　its　manufacturers　are　enabled　to　export
  to　England　and　other　countries　upwards　of　500；000　tons　a…year。　　How
  different　this　state　of　things　from　the　time　when　raids　were　made
  across　the　Border　for　the　purpose　of　obtaining　a　store　of　iron
  plunder　to　be　carried　back　into　Scotland！
  The　extraordinary　expansion　of　the　Scotch　iron　trade　of　late　years
  has　been　mainly　due　to　the　discovery　by　David　Mushet　of　the　Black
  Band　ironstone　in　1801；　and　the　invention　of　the　Hot　Blast　by　James
  Beaumont　Neilson　in　1828。　　David　Mushet　was　born　at　Dalkeith；　near
  Edinburgh；　in　1772。*
  ＇footnpote。。。
  The　Mushets　are　an　old　Kincardine　family；　but　they　were　almost
  extinguished　by　the　plague　in　the　reign　of　Charles　the　Second。　　Their
  numbers　were　then　reduced　to　two；　one　of　whom　remained　at　Kincardine；
  and　the　other；　a　clergyman；　the　Rev。　George　Mushet　；　accompanied
  Montrose　as　chaplain。　　He　is　buried　in　Kincardine　churchyard。
  。。。＇
  Like　other　members　of　his　family　he　was　brought　up　to　metal…founding。
  At　the　age　of　nineteen　he　joined　the　staff　of　the　Clyde　Iron　Works；
  near　Glasgow；　at　a　time　when　the　Company　had　only　two　blast…furnaces
  at　work。　　The　office　of　accountant；　which　he　held；　precluded　him　from
  taking　any　part　in　the　manufacturing　operations　of　the　concern。　　But
  being　of　a　speculative　and　ingenious　turn　of　mind；　the　remarkable
  conversions　which　iron　underwent　in　the　process　of　manufacture　very
  shortly　began　to　occupy　his　attention。　　The　subject　was　much　discussed
  by　the　young　men　about　the　works；　and　they　frequently　had　occasion　to
  refer　to　Foureroy's　well…known　book　for　the　purpose　of　determining
  various　questions　of　difference　which　arose　among　them　in　the　course
  of　their　inquiries。　　The　book　was；　however；　in　many　respects
  indecisive　and　unsatisfactory；　and；　in　1793；　when　a　reduction　took
  place　in　the　Company's　staff；　and　David　Mushet　was　left　nearly　the
  sole　occupant　of　the　office；　he　determined　to　study　the　subject　for
  himself　experimentally；　and　in　the　first　place　to　acquire　a　thorough
  knowledge　of　assaying；　as　the　true　key　to　the　whole　art　of
  iron…making。
  He　first　set　up　his　crucible　upon　the　bridge　of　the　reverberatory
  furnace　used　for　melting　pig…iron；　and　filled　it　with　a　mixture
  carefully　compounded　according　to　the　formula　of　the　books；　but；
  notwithstanding　the　shelter　of　a　brick；　placed　before　it　to　break　the
  action　of　the　flame；　the　crucible　generally　split　in　two；　and　not
  unfrequently　melted　and　disappeared　altogether。　　To　obtain　better
  results　if　possible；　he　next　had　recourse　to　the　ordinary　smith's
  fire；　carrying　on　his　experiments　in　the　evenings　after　office…hours。
  He　set　his　crucible　upon　the　fire　on　a　piece　of　fire　brick；　opposite
  the　nozzle　of　the　bellows；　covering　the　whole　with　coke；　and　then
  exciting　the　flame　by　blowing。　　This　mode　of　operating　produced
  somewhat　better　results；　but　still　neither　the　iron　nor　the　cinder
  obtained　resembled　the　pig　or　scoria　of　the　blast…furnace；　which　it
  was　his　ambition　to　imitate。　　From　the　irregularity　of　the　results；
  and　the　frequent　failure　of　the　crucibles；　he　came　to　the　conclusion
  that　either　his　furnace；　or　his　mode　of　fluxing；　was　in　fault；　and　he
  looked　about　him　for　a　more　convenient　means　of　pursuing　his
  experiments。　　A　small　square　furnace　had　been　erected　in　the　works　for
  the　purpose　of　heating　the　rivets　used　for　the　repair　of　steam…engine
  boilers；　the　furnace　had　for　its　chimney　a　cast…iron　pipe　six　or
  seven　inches　in　diameter　and　nine　feet　long。　　After　a　few　trials　with
  it；　he　raised　the　heat　to　such　an　extent　that　the　lower　end　of　the
  pipe　was　melted　off；　without　producing　any　very　satisfactory　results
  on　the　experimental　crucible；　and　his　operations　were　again　brought
  to　a　standstill。　　A　chimney　of　brick　having　been　substituted　for　the
  cast…iron　pipe；　he　was；　however；　enabled　to　proceed　with　his　trials。
  He　continued　to　pursue　his　experiments　in　assaying　for　about　two
  years；　during　which　he　had　been　working　entirely　after　the　methods
  described　in　books；　but；　feeling　the　results　still　unsatisfactory；　he
  determined　to　borrow　no　more　from　the　books；　but　to　work　out　a　system
  of　his　own；　which　should　ensure　results　similar　to　those　produced　at
  the　blast…furnace。　　This　he　eventually　succeeded　in　effecting　by
  numerous　experiments　performed　in　the　night；　as　his　time　was　fully
  occupied　by　his　office…duties　during　the　day。　　At　length　these　patient
  experiments　bore　their　due　fruits。　　David　Mushet　became　the　most
  skilled　assayer　at　the　works；　and　when　a　difficulty　occurred　in
  smelting　a　quantity　of　new　ironstone　which　had　been　contracted　for；
  the　manager　himself　resorted　to　the　bookkeeper　for　advice　and
  information；　and　the　skill　and　experience　which　he　had　gathered
  during　his　nightly　labours；　enabled　him　readily　and　satisfactorily　to
  solve　the　difficulty　and　suggest　a　suitable　remedy。　　His　reward　for
  this　achievement　was　the　permission；　which　was　immediately　granted
  him　by　the　manager；　to　make　use　of　his　own　assay…furnace；　in　which　he
  thenceforward　continued　his　investigations；　at　the　same　time　that　he
  instructed　the　manager's　son　in　the　art　of　assaying。　　This　additional
  experience　proved　of　great　benefit　to　him；　and　he　continued　to
  prosecute　his　inquiries　with　much　zeal；　sometimes　devoting　entire
  nights　to　experiments　in　assaying；　roasting　and　cementing　iron…ores
  and　ironstone；　decarbonating　cast…iron　for　steel　and　bar…iron；　and
  various　like　operations。　　His　general　practice；　however；　at　that　time
  was；　to　retire　between　two　and　three　o'clock　in　the　morning；　leaving
  directions　with　the　engine…man　to　call　him　at　half…past　five；　so　as
  to　be　present　in　the　office　at　six。　　But　these　praiseworthy
  experiments　were　brought　to　a　sudden　end；　as　thus　described　by
  himself：
  〃In　the　midst　of　my　career　of　investigation；〃　says　he；*
  ＇footnote。。。
  Papers　on　Iron　and　Steel。　　By　David　Mushet。　　London；　1840。
  。。。＇
  〃and　without　a　cause　being　assigned；　I　was　stopped　short。　　My
  furnaces；　at　the　order　of　the　manager；　were　pulled　in　pieces；　and　an
  edict　was　passed　that　they　should　never　be　erected　again。　　Thus
  terminated　my　researches　at　the　Clyde　Iron　Works。　　It　happened　at　a
  time　when　I　was　interestedand　I　had　been　two　years　previously
  occupiedin　an　attempt　to　convert　cast…iron　into　steel；　without
  fusion；　by　a　process　of　cementation；　which　had　for　its　object　the
  dispersion　or　absorption　of　the　superfluous　carbon　contained　in　the
  cast…iron；an　object　which　at　that　time　appeared　to　me　of　so　great
  importance；　that；　with　the　consent　of　a　friend；　I　erected　an　assay
  and　cementing　Furnace　at　the　distance　of　about　two　miles　from　the
  Clyde　Works。　　Thither　I　repaired　at　night；　and　sometimes　at　the
  breakfast　and　dinner　hours　during　the　day。　　This　plan　of　operation　was
  persevered　in　for　the　whole　of　one　summer；　but　was　found　too
  uncertain　and　laborious　to　be　continued。　　At　the　latter　end　of　the
  year　1798　I　left　my　chambers；　and　removed　from　the　Clyde　Works　to　the
  distance　of　about　a　mile；　where　I　constructed　several　furnaces　for
  assaying　and　cementing；　capable　of　exciting　a　greater　temperature
  than　any　to　which　I　before　had　access；　and　thus　for　nearly　two　years
  I　continued　to　carry　on　my　investigations　connected　with　iron　and　the
  alloys　of　the　metals。
  〃Though　operating　in　a　retired　manner；　and　holding　little
  communication　with　others；　my　views　and　opinions　upon　the　RATIONALE
  of　iron…making　spread　over　the　establishment。　　I　was　considered
  forward　in　affecting　to　see　and　explain　matters　in　a　different　way
  from　others　who　were　much　my　seniors；　and　who　were　content　to　be
  satisfied　with　old　methods　of　explanation；　or　with　no　explanation　at
  all。。。。。　　Notwithstanding　these　early　reproaches；　I　have　lived　to　see
  the　nomenclature　of　my　youth　furnish　a　vocabulary　of　terms　in　the　art
  of　iron…making；　which　is　used　by　many　of　the　ironmasters　of　the
  present　day　with　freedom　and　effect；　in　communicating　with　each　other
  on　the　subject　of　their　respective　manufactures。　　Prejudices　seldom
  outlive　the　generation　to　which　they　belong；　when　opposed　by　a　more
  rational　system　of　explanation。　　In　this　respect；　Time　（as　my　Lord
  Bacon　says）　is　the　greatest　of　all　innovators。
  〃In　a　similar　manner；　Time　operated　in　my　favour　in　respect　to　the
  Black　Band　Ironstone。*
  ＇footnote。。。
  This　valuable　description　of　iron　ore　was　discovered　by　Mr。　Mushet；
  as　he　afterwards　informs　us　（Papers　on　Iron　and　Steel；　121）；in　the
  year　1801；　when　crossing　the　river　Calder；　in　the　parish　of　Old
  Monkland。　　Having　subjected　a　specimen　which　he　found　in　the　river…bed
  to　the　test　of　his　crucible；　he　satisfied　himself　as　to　its
  properties；　and　pr