THE ROYAL ARTILLERY INSTITUTION. 
221 
ON THE DURATION OE WOODEN CARRIAGES IN 
A HOT CLIMATE. 
By Lieut.-Col. H. CLERK, R.A., E.R.S. 
The return to this country of a large portion of the carriages, platforms, 
&c. which were on the fortifications of Corfu, has afforded a favourable 
opportunity of estimating the probable duration of wooden carriages, a 
subject which has a peculiar interest at the present moment when the 
substitution of wrought-iron for wood in carriages and platforms is under 
consideration. 
It has been generally supposed that 10 years is about the time that a 
carriage will last, when constantly exposed to the weather ; but the result of 
the present investigation is, that 29^ years represents the average duration, 
and this in a climate where the sun has a powerful effect on wood. The 
newest and best of the carriages have been landed at Malta and only the 
worst returned to this country; if all had been included in the comparison 
the result would be still more favourable. Most of these carriages are of 
“English oak,” and some made as far back as 1805 are still fit for service. 
By “average duration” is understood, that period when, out of any 
number of carriages, the chances are, that the proportion of serviceable to 
unserviceable will be equal. Reference being had merely to the effects of 
age and climate, not to the wear and tear from constant use. 
Tables I. and II. give the description of carriage, date of manufacture and 
present state. Table III. gives the dates, length of service and condition, 
arranged according to years. Table IY. is formed from Table III., by 
collecting the numbers into periods of 10 years. The proportion is obtained 
by dividing the number of serviceable and unserviceable in each period, by 
the total number issued in that period. As the date has been found on all 
carriages since 1805, those without date are supposed to have been made 
previously. 
It will be seen on inspection of Table IY. that out of 338 carriages, &c. 
returned to this country from Corfu, there are 138 still fit for service, 200 
that are unserviceable, but of these 16 have become so through wear and 
tear, consequently only 184 are worn out from age. Of the 138 serviceable, 
25 were made upwards of 50 years ago. Erom this table it appears that the 
average duration is about 29^ years, and that 17 out of 1000 carriages will 
become unserviceable annually. 
Table Y. gives the probable number, out of 1000, of serviceable and 
unserviceable carriages for every 5 years up to 58’8 years, when the whole 
