5i6 



NATURE 



[July 17, 1913 



of air. An experimental plant has been erected at 

 the University of Manchester, which will permit of 

 accurate observations of this process and the collec- 

 tion of further detail. 



Mr. F. Southerden has extended the investigations 

 made at Leeds, Glasgow, and London, upon atmo- 

 spheric pollution, to the atmosphere over the city of 

 Exeter and its immediate surroundings. He finds 

 that rain-water collected- less than a mile from the 

 centre of the city is very noticeably superior to that 

 collected more centrally, the proportion of dissolved 

 solids and sulphate reaching only about one-half, but 

 there is no marked difference as regards the chlorine 

 or ammonia, and so he concludes that these are 

 derived in the main from sources other than coal 

 smoke. The experiments make it clear that the atmo- 

 spbj ric pollution of Exeter, though less in amount, 

 is similar in its nature to that in larger towns._ 



Mr. Southerden also gave the results of his inves- 

 tigations upon the effect of coal smoke on the stone- 

 work of Exeter Cathedral. The stonework consists 

 of limestone of varying quality and texture, and the 

 oxy-acids of sulphur derived from the combustion of 

 coal convert the calcium carbonate of the stone into 

 soluble calcium sulphate, and the surface of the stones 

 slowly crystallises and expands in such a way that 

 disintegration results. The author concludes that the 

 exact conditions which lead to scaling are not simple, 

 but the extent of sulphate formation appears to be an 

 important factor, and the destructive influence of 

 sulphuric acid is doubly important, for in the more 

 sheltered situations it leads to disintegration by scal- 

 ing, and in exposed positions calcium sulphate is 

 formed and dissolved away, thus hastening the de- 

 struction brought about by more natural agencies, 

 such as frost, wind, and rain. The blackening which 

 is verv noticeable on portions of the stone structure 

 is due to a thin film of soot, from which it has been 

 possible to extract a small amount of tar. 



REPORT OF THE ADVISORY COMMITTEE 

 ON FORESTRY. 



A FEW weeks ago was issued a Blue-book of 

 •**- general interest, the Report of the Advisory 

 Committee on Forestry for the period July to October, 

 1912 (Cd. 6713, price 6d.). The Advisory Committee 

 on Forestry comprises such well-known names as 

 Sir E. Stafford Howard, Sir S. Eardley-Wilmot (late 

 Inspector-General of Forests, India), Sir D. Prain 

 (director of Kew), Sir William Schlich (the Oxford 

 professor of forestry), and Prof. Somerville, of the 

 Oxford School of Rural Economics, who is perhaps 

 as well known for his writings on forestry as for 

 those on agriculture; and Mr. E. R. Pratt, president 

 of the Royal English Arboricultural Society. Of the 

 ten members of the Committee only four are profes- 

 sional foresters, so that the professional element is not 

 even in a majority. Mr. R. L. Robinson, the chief of 

 the forestry branch of the Board of Agriculture 

 and Fisheries, fulfills the office of secretary to 

 the Advisory Committee, and is apparently the author 

 of the two chief appendices to the report, though one 

 of these is not signed. These appendices, on forest 

 research and development, contain a mass of technical 

 information and interesting general observations, which 

 will well repay perusal by those interested in British 

 forestry. 



The Blue-book contains the advice of the Forestry 

 Committee on three questions submitted to it for 

 opinion by Mr. Runciman. 



The first of these questions relates to forest surveys, 

 which it is advised should be divided into two classes : 

 (a) preliminary or flying surveys, (6) detailed surveys. 

 NO. 228l, VOL. 91] 



The surveys proposed should bring together much 

 useful information, and supply a long-felt want in 

 the cartography of these islands. We have excellent 

 geological, topographical, meteorological, and other 

 maps; but he wdio wishes to see what is the extent 

 and value of the woodlands must be satisfied with 

 the ordinary ordnance maps and a few forest maps. 

 The ordnance maps give no indication of the quality, 

 and are often misleading as to the quantity, of the 

 forest. Yet few of the special maps that exist have 

 the importance of a forest map, with the national issue 

 of 30,000,000!. yearly sent out of the country for 

 timber and forest produce, which could be produced 

 easily in these islands ! The extension of forest sur- 

 veys is therefore an excellent scheme, which should 

 meet with universal approval. 



When, however, we go on to read that surveys of 

 both types are necessary " as a preliminary step to- 

 wards the inauguration of afforestation operations," 

 the forest surveys assume a sinister aspect. If they 

 are to be taken as an excuse for postponing the com- 

 mencement of practical forestry, the country will be 

 better without them. This, perhaps, is w'hy Mr. 

 Munro Ferguson adds his rider to the report : "I am 

 of opinion that 2000/. is a sufficient sum to apply for 

 survey work for the next two years, after which the 

 expenditure could be reviewed in the light of experi- 

 ence." In the estimate at p. 50, the total cost of the 

 surveys is given at 35,000/., and the time at eleven 

 years; and this is for" a partial survey, not embracing 

 the whole of the seven areas mentioned in the report 

 of the Advisory Committee. These seven areas for 

 the forest surveys are : — 



1. South Wales. 



2. North Wales. 



3. Westmorland, Cumberland, and Northumberland. 



4. Kent, Surrey, and Sussex. 



5. Berks, Hants, Wilts, and Dorset. 



6. Derby, Lancashire, and the_West Riding. 



7. Lincoln, Norfolk, Suffolk, and Essex. 



It is recommended that surveys be begun in dis- 

 tricts 1, 3, 4, and 7, and that in conducting 

 these preliminary surveys use should be made to the 

 fullest extent of the knowledge which local owners, 

 foresters, and agents possess. The cooperation of the 

 Royal English Arboricultural Society and of local com- 

 mittees is also invited. This is excellent. 



The report expresses doubts as to the advisability of 

 publishing these forest surveys. It is not clear 

 wherein lies the difficulty of doing so, but obviously 

 they should be of much general utility, both to the 

 public at large and the student of forestry. 



The second question on which the advice of the 

 Forestry Committee has been asked relates to "demon- 

 stration areas." These have figured largely in British 

 forest literature of recent years, and the Advisory 

 Committee states that " it has received their very care- 

 ful consideration " (though, indeed, this phrase is re- 

 peated in the answer to each question). It seems 

 possible that forest demonstration areas are one of 

 those side issues which during the last three years in 

 British forestry have served to distract attention from 

 the main question — the inauguration of practical 

 forestry by the acquisition and planting of ground on 

 a large scale. Here Mr. Munro Ferguson has added 

 another rider which will receive the hearty approval 

 of every forester — " I agree with paragraph 6, that 

 the Forest of Dean, with the adjoining Crown woods, 

 is well suited to meet the requirements imposed by 

 a demonstration forest, and am of opinion, therefore, 

 that the whole area should be removed from the 

 control of the deputy-surveyor and placed under a 

 trained forest officer." Some years ago, when the 

 post of deputy-surveyor of the Forest of Dean became 



