SCIENTIFIC SUMMARY. 127 
same influences, a few only have succumbed to the trying conditions by 
which they are surrounded, the rest remaining apparently uninjured. 
In searching for the primary causes which are likely to be operating 
adversely in all these instances, it is not necessary to look far to discover 
the evidence of a damp atmosphere, and considerable fluctuations in tem- 
perature, as being paramount among the causes that have occasioned so 
much destruction. The glass-plate in front of the pictures is frequently 
bedimmed with a film of dew, and the mounting cards are, like the photo- 
graphs, manifestly affected by damp, several of them having become 
spotted with mildew ; this is especially the case with the show-frames of 
the London School of Photography, and those of Mr. Warner, of Ross. 
The beautiful view of Buttermere, exhibited by Mr. James Mudd, and 
hanging beside the former on the same wall, is also the victim of circum- 
stances which are plainly indicated by the growth of mildew on the 
mounting-card ; while, strange to say, an excellent print of the South 
Stack Lighthouse, by the same artist, and placed contiguous, has resisted 
perfectly the action of moisture. The other works by Mr. Mudd are 
hanging chiefly on the central screen in the photographic gallery, where 
they are considerably less liable to be affected by damp, and have conse- 
quently preserved all the delicacy and beauty of toning for which the 
photographs by this gentleman have long been celebrated. 
The same remark applies to the pictures exhibited by Mr. Vernon 
Heath; to the views in North Wales, by Mr. Henry White, and by Mr. 
Sidebotham ; to those of Mr. D. Campbell, of Ayr ; and likewise to the 
exquisite landscapes in Madeira, by Mr. R. M. Gordon : none of these 
disclose the least symptom of fading, and all are placed upon the central 
screens. In like manner, with regard to the portraits by Mr. T. R. 
Williams, and to the magnificent series of abbeys and cathedrals by Mr. 
Francis Bedford, not one of these shows the least indication of fading ; but 
it must be stated that they occupy the more favoured position in the centre 
of the gallery. 
A remarkable instance of the formation of mildew is apparent on the 
leather binding of a book exhibited by Mr. A. W. Bennett, and entitled 
“ The Ruined Abbeys and Castles of Great Britain, illustrated by Photo- 
graphy.” This book is inclosed within a glass case, and hangs directly in 
contact with the wall. Some few of the exhibitors appear, however, to 
have adopted the suggestion of Mr. G. Wharton Simpson, and have 
inserted pieces of cork between their frames and the objectionable wall ; 
the advantage gained by this precaution is already manifest by the pro- 
tection afforded to these prints. 
As the general conclusion, from observations made upon the photo- 
graphs now on view at the International Exhibition, it must be admitted, 
that the security of a photographic record depends, not merely upon the 
amount of care bestowed originally upon its preparation, but quite as 
much upon its being preserved in such a manner as to exclude, as far as 
possible, the adverse influences of damp, or actual contact with moisture, 
produced by condensation on the front glass : conditions to be fulfilled 
which, as yet, do not appear to have received their merited share of 
attention. 
