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good workman merely turning a handle； without any shoulder
work。' He evidently did not anticipate any great results from my
engineering education。 But we all know what machine tools are
doing now；and where should we be without them？〃
Watt withdrew from the firm in 1800； on the expiry of his patent
for the condensing steam…engine； but Boulton continued until the
year 1809； when he died full of years and honours。 Watt lived on
until 1819。 The last part of his life was the happiest。 During
the time that he was in the throes of his invention； he was very
miserable； weighed down with dyspepsia and sick headaches。 But
after his patent had expired； he was able to retire with a
moderate fortune； and began to enjoy life。 Before； he had
〃cursed his inventions；〃 now he could bless them。 He was able to
survey them； and find out what was right and what was wrong。 He
used his head and his hands in his private workshop； and found
many means of employing both pleasantly。 Murdock continued to be
his fast friend； and they spent many agreeable hours together。
They made experiments and devised improvements in machines。 Watt
wished to make things more simple。 He said to Murdock； 〃it is a
great thing to know what to do without。 We must have a book of
blotsthings to be scratched out。〃 One of the most interesting
schemes of Watt towards the end of his life was the contrivance
of a sculpture…making machine； and he proceeded so far with it as
to to able to present copies of busts to his friends as 〃the
productions of a young artist just entering his eighty…third
year。〃 The machine； however； remained unfinished at his death；
and the remarkable fact is that it was Watt's only unfinished
work。
The principle of the machine was to carry a guide…point at one
side over the bust or alto…relievo to be copied； and at the other
side to carry a corresponding cutting…tool or drill over the
alabaster； ivory； jet； or plaster of Paris to be executed。 The
machine worked； as it were； with two hands； the one feeling the
pattern； the other cutting the material into the required form。
Many new alterations were necessary for carrying out this
ingenious apparatus； and Murdock was always at hand to give his
old friend and master his best assistance。 We have seen many
original letters from Watt to Murdock； asking for counsel and
help。 In one of these； written in 1808； Watt says： 〃I have
revived an idea which； if it answers； will supersede the frame
and upright spindle of the reducing machine； but more of this
when we meet。 Meanwhile it will be proper to adhere to the
frame； etc。； at present； until we see how the other alterations
answer。〃 In another he says： 〃I have done a Cicero without any
plaitsthe different segments meeting exactly。 The fitting the
drills into the spindle by a taper of 1 in 6 will do。 They are
perfectly stiff and will not unscrew easily。 Four guide…pullies
answer； but there must be a pair for the other end； and to work
with a single hand； for the returning part is always cut upon
some part or other of the frame。〃
These letters are written sometimes in the morning； sometimes at
noon； sometimes at night。 There was a great deal of
correspondence about 〃pullies；〃 which did not seem to answer at
first。 〃I have made the tablets；〃 said Watt on one occasion；
〃slide more easily； and can counterbalance any part of their
weight which may be necessary； but the first thing to try is the
solidity of the machine； which cannot be done till the pullies
are mounted。〃 Then again： 〃The bust…making must be given up
until we get a more solid frame。 I have worked two days at one
and spoiled it； principally from the want of steadiness。〃 For
Watt； it must be remembered； was now a very old man。
He then proceeded to send Murdock the drawing of a 〃parallel
motion for the machine；〃 to be executed by the workmen at Soho。
The truss braces and the crosses were to be executed of steel；
according to the details he enclosed。 〃I have warmed up；〃 he
concludes； 〃an old idea； and can make a machine in which the
pentagraph and the leading screw will all be contained in the
beam； and the pattern and piece to be cut will remain at rest
fixed upon a lath of cast iron or stout steel。〃 Watt is very
particular in all his details： 〃I am sorry；〃 he says in one note；
〃to trouble you with so many things； but the alterations on this
spindle and socket ＇he annexes a drawing＇ may wait your
convenience。〃 In a further note； Watt says。 〃The drawing for
the parallel lathe is ready； but I have been sadly puzzled about
the application of the leading screws to the cranes in the other。
I think； however； I have now got the better of the difficulties；
and made it more certain； as well as more simple； than it was。 I
have done an excellent head of John Hunter in hard white in
shorter time than usual。 I want to show it you before I repair
it。〃
At last Watt seems to have become satisfied： 〃The lathe；〃 he
says； 〃is very much improved； and you seem to have given the
finishing blow to the roofed frame； which appears perfectly
stiff。 I had some hours' intense thinking upon the machine last
night； and have made up my mind on it at last。 The great
difficulty was about the application of the band； but I have
settled it to be much as at present。〃
Watt's letters to Murdock are most particular in details；
especially as to screws； nuts； and tubes； with strengths and
dimensions； always illustrated with pen…and…ink drawings。 And
yet all this was done merely for mechanical amusement； and not
for any personal pecuniary advantage。 While Watt was making
experiments as to the proper substances to be carved and drilled；
he also desired Murdock to make similar experiments。 〃The
nitre；〃 he said in one note； 〃seems to do harm； the fluor
composition seems the best and hardest。 Query； what would some
calcined pipe…clay do？ If you will calcine some fire…clay by a
red heat and pound it；about a pound；and send it to me； I
shall try to make you a mould or two in Henning's manner to cast
this and the sulphur acid iron in。 I have made a screwing tool
for wood that seems to answer； also one of a one…tenth diameter
for marble； which does very well。〃 In another note； Watt says：
〃I find my drill readily makes 2400 turns per minute； even with
the large drill you sent last； if I bear lightly； a three…quarter
ferril would run about 3000； and by an engine that might be
doubled。〃
The materials to be drilled into medallions also required much
consideration。 〃I am much obliged to you；〃 said Watt； 〃for the
balls； etc。； which answer as well as can be expected。 They make
great progress in cutting the crust （Ridgways） or alabaster； and
also cut marble； but the harder sorts soon blunt them。 At any
rate； marble does not do for the medallions； as its grain
prevents its being cut smooth； and its semi…transparence hurts
the effect。 I think Bristol lime； or sh