636 



NATURE 



[October 22, 1908 



theoretical and practical investigation. The value of b, 

 in van der Waals's equation, was assumed to be 00005 

 with a negligible a (Onnes and Keeson), and this is 

 in agreement with the value of 0^000432 calculated 

 from the isotherms at and above —217° C. (Onnes). 

 From the observations on the liquid, however, it 

 would seem that the value of h should be o'oooy there, 

 and that a must have a positive value of o'oooo5 

 (Onnes). Lastly, the lowest steady temperature 

 known was obtained by boiling' helium at a pressure 

 of not more than i cm., at which the temperature 

 could not have been much above 3°'o K. The liquid 

 was mobile and perfectly clear, and no trace of solid 

 was visible, so that a still lower steady temperature is 

 clearly attainable (Onnes). Francis Hvndman. 



THE INTERNATIONAL CONGRESS ON ROADS. 

 'T'HE first International Road Congress was held in 



-'■ Paris during the week which ended on Satur- 

 day last, October 17. On the whole the congress 

 may be pronounced a success, chiefly on account of 

 the large number of interested visitors present, and 

 from the fact that on certain points there was a strong 

 consensus of opinion that roads can now be con- 

 structed to stand modern automobile traffic at slight 

 additional cost, and that the two nuisances dust in 

 summer and mud in winter can be greatly minimised 

 in their extent. 



The congress, though not whollv official, received 

 the support of the French Government. The letters 

 of invitation and explanatory circulars were sent out 

 from the general secretary of the Ministere de Travaux 

 publics; consequently the invitations were not confined 

 to delegates sent by the Governments of the various 

 countries represented, but were sent to representative 

 public bodies, road authorities, automobile clubs, and 

 to engineers and other members of the public who are 

 likely to have knowledge and be interested in tlie 

 great question of road communications. 



The attendance at the meetings was generally very 

 good ; the rooms were crowded. As is usual, the hos- 

 pitality shown by the French in the way of fetes and 

 excursions made the week very enjoyable to the 

 French provincial visitors as well as to the foreign 

 visitors. The first reception was at the Sorbonne, 

 afterwards a grand evening reception at the Hotel 

 des Invalides, a gala performance at the Com^die 

 Frangaise, and a final sitting at the Sorbonne on 

 Saturday morning^ announcing- the results obtained. 



The general procedure was as follows. Early in 

 the year requests were sent to all the interested 

 countries that contributions should be submitted in 

 the form of short papers, which would be printed 

 and circulated previous to the congress, the substance 

 of which would be collected by a reporter of each of 

 the groups, and on which discussions would take 

 place. The subjects on which these memoirs were 

 invited were the following : — General reports on the 

 construction and maintenance of existing roads, 

 special repoits on the cost of road-bed and methods of 

 construction of roads ; special reports on maintenance 

 questions — on this group of construction and main- 

 tenance of roads thirty-two papers were received, of 

 which seven were by English contributors. 



The second group of questions related to that part 

 of road construction and maintenance which was 

 rightly named at the congress " the present struggle 

 against the wear and the dust." These included 

 methods of cleaning and washing, and questions were 

 specially put asking for experience in the use of tar 

 or similar insoluble binding materials. Twentv-two 

 papers were received in this group, five of them by 

 English authors. Another group was on the roads of 



KO. 2034, \'OL. 78] 



the future. On this question fifteen papers were 

 received, none of them by English authors. 



The remaining questions were those relating to 

 traific, damage caused to the roads bv speed or by 

 the weight of the vehicles, by pneumatic t3res, anti- 

 skidding devices and similar matters. To this ques- 

 tion sixteen papers were specially addressed, half of 

 them by Englishmen. Then came seven papers, all 

 by Frenchmen, on road signalling and milestones; and 

 finally six papers on public vehicles used on the road- 

 way, including tramway services. Five of these were 

 by Frenchmen and one by a Spanish engineer. 



Altogether ninety-eight papers were contributed, 

 printed and circulated previous to the congress to all 

 the subscribing members. This part of the work 

 was splendidly done. The papers were sent in in their 

 original language ; in many cases they were com- 

 pletely translated ; in some cases summaries were 

 made in more than one language. It will be seen 

 that about one-fifth of the whole of the papers came 

 from England. 



The discussions were divided into two sections, first 

 those chiefly relating to road construction, and second 

 those relating to the use of the roads and the vehicles 

 running on them. They were held in the old tennis 

 court at the corner of the Tuileries Gardens next to 

 the Place de la Concorde, and on the plateau imme- 

 diately surrounding this building were grouped a 

 large number of modern appliances used on the roads, 

 such as road rollers, road repairing machines, 

 machinery for brushing and watering by horse-power 

 and by automobile power, and, lastly, a long array 

 of machines for distributing tar or other bituminous 

 compounds on the road to render it waterproof and 

 dustless. Inside the building a number of smaller 

 exhibits were shown of various road materials and 

 specimens cut out of existing roads, the latter being 

 chiefly found on a collective English exhibit. 



As stated at the commencement of this article, the 

 success of the congress laid chiefly in the interest 

 which it excited, and in the fact that for the first 

 time a large number of road engineers and of those 

 interested in the use of roads were brought together 

 in a very pleasant manner, and, as is usual at these 

 meetings, a great many useful friendships were formed 

 which will undoubtedly lead to the better circulation 

 of new ideas on road construction. 



The number of English professional visitors was 

 very large. Among the English visitors were found 

 chairmen of the county councils, many of the most 

 prominent county engineers, with a large sprinkling 

 of municipal men and of surveyors of the various rural 

 districts. As might be expected, a very considerable 

 number of these gentlemen were not sufficiently fami- 

 liar with French to follow the debates, which for the 

 most part were conducted in French. 



At an early stage it became evident that the know- 

 ledge possessed by some of the English visitors was 

 very valuable to the congress, but that there was a 

 great risk of their experience being lost, so that it 

 was decided to hold supplementary meetings of the 

 English-speaking, i.e. the English and American, 

 visitors, previous to the regular meetings, and this 

 course, although at first sight it might have seemed 

 as if the English-speaking races wished to be exclu- 

 sive, turned out to be of use. The results of the dis- 

 cussions by the English-speaking sections were dele- 

 gated to one or two speakers, who afterwards com- 

 municated them during the main debates. In this 

 way some useful resolutions were carried which 

 cannot now be given, as they were not printed or 

 agreed to in detail when the writer left Paris imme- 

 diately after the final sitting on Saturday ; but, speak- 

 ing generally, it may be said that a great many of 



