34 Transactions.—JMiscellaneous. 
non-conductor. To prevent a circulation of cold air from end to end of the 
boiler, I attached a piece of sheet-iron, cut to the circumference of the boiler, 
to the ends of the battens on the grids at each end of the boiler G (Fig. 1). 
A coat of paint on the canvas completed the apparatus. 
I exhibit a full-size section of one of the grids, with felt and canvas 
attached, to be placed for reference in the Museum of the Society at 
Auckland. I have attached the felt to the grid in this section to show the 
apparatus complete ; but, in practice, the felt and canvas only are attached to 
each other, but not to the grid, so that each can be stripped from the boiler 
without difficulty. 
I come now to results. I find that loss by radiation and condensation is 
reduced to a minimum ; the canvas covering of the boiler being always quite 
cool, with steam at 50105. As an instance, I may mention that when the 
engines stop at 6 o'clock p.m. with steam at 5OlIbs., with the felt on, at 6 o'clock 
next morning steam is about 25105, ; without the felt, steam goes down to nil 
before 6 o'clock next morning, the dampers being in both cases the same. The 
saving of coal has, of course, been considerable. Nine months have elapsed 
since I applied this mode of felting at my own works, and I find that both 
wood and felt are practically uninjured. 
Where compound engines are in use, this mode of felting the steam pipes 
leading from the boilers to the high-pressure engine, and from the high- 
pressure to the condensing cylinder, will be found most effectual in preventing 
loss by condensation or radiation, besides being comparatively indestructible. 
For covering steam domes and engine cylinders it is equally effective. For 
these latter the grids and felt may be covered with wooden battens, hooped 
and varnished as usual. 
It will be necessary to observe, when covering pipes or other steam 
chambers of small diameter, that the cranked pieces of hoop-iron must be 
placed sufficiently near to each other to secure a space of 3 in. or 4 in. between 
the steam-pipe and felt. In all cases it will be found more practicable to run 
the pieces of plane hoop-iron round the pipes or cylinders to be covered, 
running the cranked pieces longitudinally, as already described in the case of 
steam boilers. 
