eee 
Moveable- Derrick Crane. 65 
ought to be particularly attended to,—never to allow any 
workman to guide or shift the machinery without having been 
trained a little to its management ; as the most trifling error, 
such as neglecting to let down the click of the ratchet-wheel, 
when throwing out of gearing the handles, after lowering the 
derrick, might be productive of serious consequences ; while, 
on the other hand, with a little experience and attention, no- 
thing can be more safe. 
Fig. 2. exhibits the reverse side of the crane from Fig. 1, 
but on a little larger scale. 
I will not trespass farther on the Society’s time than merely 
to solicit your attention to another useful mode of its appli- 
cation, whereby the contractors for Burntisland Low-Water 
Pier have been enabled to construct, and carry out seawards, 
the whole of the timber stageing for working their diving- 
bell. 
The saving in time and expense from this method has been 
great. The small model is intended to represent one 40 feet 
length of stageing with the crane in advance, ready for plac- 
ing another 40 feet length out seawards. 
I respectfully beg to state, that I believe no printed de- 
scription of the improved moveable-derrick crane has ever 
yet been given to the public ; and that it is now, with a few 
exceptions, unknown in England. 
TRINITY CRESCENT, 3d April 1844, 
Report by the Committee of the Royal Scottish Society of Arts on 
Mr Wightman’s Improved Moveable-Derrick Crane. 
June 6. 1844.—The Committee have carefully examined the model, 
drawings, and description of this crane, submitted to them by the Society; 
and having compared it with other machines of a similar description pre- 
viously in use, are satisfied that Mr Wightman has introduced very de- 
cided improvements in this highly useful engine. 
The use of the moveable-jib, or derrick, is not new ; but it has now, by 
these improvements, been reduced to so great a degree of simplicity, as 
leaves little farther to be done or wished for, to render its operation 
complete ; and by this invention, and particularly by its introduction 
in the operations of Granton Pier, from whence its use has been ex- 
VOL. XXXVIII. NO. LXXV.—JAN. 1845. Ki 
