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XII. On the Redstance of Glass Globes and Cylinders to Collapse from external pressure ; 
and on the Tensile and Compressive Strength of various kinds of Glass. 
ByW. Faiebaiest, Esq., C.E., F.R.S., and Thomas Tate, Esq. 
Received May 3, — Read May 12, 1859. 
The recently published experiments upon the coUapse of tubes of wrought iron *, led to 
results so novel and so much at variance with the ordinary rules of practice, as to exem- 
plify anew the caution and diligence which are requisite in investigating the physical 
laws of nature, in order to arrive at just conclusions in regard to the properties of 
materials and their most ejSective distribution for the purposes of construction. 
In the experiments alluded to, it was clearly shown that the prevailing ideas of the 
strength of vessels subjected to a uniform external force were erroneous and at variance 
with the laws of resistance to collapse under such circumstances ; whilst in practice the 
prevalence of error in this matter had led to serious and sometimes fatal accidents, 
arising out of the construction of vessels of inadequate strength to sustain the pressures 
placed upon them. These errors, it is hoped, need no longer be perpetuated : the expe- 
riments on wrought iron indicated a means of increasing the strength of boiler flues and 
other vessels of that material, subjected to a collapsing force, to any required amount ; and 
this was the immediate practical application of the general law then discovered, that the 
strength of cylindrical vessels, exposed to a uniform external force, varied inversely as 
the length between the rigid ends. 
The results deduced from the experiments on tubes composed of riveted plates were 
so important as to suggest further inquiry, under the same conditions of rupture, but 
with other materials, difiering in their physical properties from wrought iron. The 
joints in the tubes employed in those experiments were defects the influence of which 
might be determined by experiments upon homogeneous vessels. The ductile yielding 
character of wrought iron suggested the extension of the experiments to hard, rigid 
materials, more capable of retaining their form under pressure. 
To fulfil the conditions thus sought for, glass was selected for experiment, as a mate- 
rial difiering totally in character from wrought iron, and on that account well fitted to 
supply data for extending our knowledge of the laws of collapse. Of vitreous structure, 
rigid, elastic, and brittle, and of low tenacity, it possessed the further advantage of being 
easily obtained and blown into homogeneous vessels of the required forms. But there 
were other reasons which had weight in making this selection. Our acquaintance with 
* Philosopliical Transactions, 1858, pp. 389 — 113. Erratum in that paper : at page 408, in the place 
of “ and by an obvious transformation,” read “ and when A='043, by an obvious transformation”. 
MDCCCLIX. 2 G 
