348 
The righting of the power situation requires (1) 
the establishment of a comprehensive system of 
electric transmission lines to be administered as a 
common-ecarrier system like the railways. (2) The 
provision of such a system will necessitate the co- 
ordinated growth of central power stations in coal 
fields and at water-power sites, and in doing so 
will open to business enterprise a tremendous field 
of opportunity hitherto closed off from entry, and 
thus lead to the balanced development of the two 
major energy resources, coal and water-power. 
(3) The principle of multiple production, recog- 
nized and incorporated in national policy, will 
supplement the additional service gained through 
the organized employment of the electrical prin- 
ciple; applied to the production of coal-generated 
electricity, and, through the medium of municipal 
publie utility plants, to the distributive employ- 
ment of coal, this principle will effectively corre- 
late the recovery of the commodity and energy 
values, so as ultimately to effect a full saving of 
the former and an increased gain of the latter, thus 
permitting a further relative diminution of the 
amount of fuel calling for transportation in bulky 
form. The first two points reduce themselves to a 
single issue, which is purely a business proposition 
to be handled by a business organization; the 
third item is more intangible and it is a matter of 
policy, which, therefore, can not be delegated or 
otherwise handled in objective fashion. 
The provision of a common-earrier system of 
transmission lines, in brief, is the key to the whole 
problem. Its establishment will remove the retard- 
ing influence of high interest rates and antagon- 
istic misunderstanding that has blocked water- 
power development, and will afford the point of 
departure from precedent in favor of coal-field 
generation of electricity. Owing to the magnitude 
of the issue and the manifold lines of progress di- 
rectly at stake, the development will provide a nu- 
clear point for the establishment of a constructive 
economic policy, needed not merely for the full de- 
velopment of this field but as well for proper un- 
foldment of the industrial possibilities of the 
country in general. As such a policy has not de- 
veloped in the past because of economic sectional- 
ism growing chiefly out of an unequalized develop- 
ment of the energy resources, the nationalization of 
industrial opportunity attainable through a bal- 
anced development of power supply will clear the 
path of the main obstruction to unified action. 
Thus specific action in respect to establishing a 
common-earrier system adapted to the power needs 
of the country will not only go far toward solving 
SCIENCE 
[N. 8S. Vou. XLVIIT. No. 1240 
the problem of transportation, but it will improve 
the fuel supply, correct the economic fallacy of 
drawing upon capital resources while neglectful of 
income, contribute to the recovery of the values 
now lost in the consumption of raw coal, lead to an 
adequate development of electrochemical activities, 
cut off a needless annual expenditure running well 
beyond the billion dollar mark, and constitute a 
potent contribution in the direction of stimulating 
the upgrowth of a constructive economic policy 
of national scope attuned to the needs of modern 
industrial development. It is believed that these 
results would involve national economies, offsetting 
in large part the cost of the war. 
SPECIAL ARTICLES 
THE COEFFICIENT OF EXPANSION OF LIVING 
TREE TRUNKS 
THE present investigation was undertaken 
as a continuation of the work of the late Pro- 
fessor C. C. Trowbridge, of the Department of 
Physics, Columbia University, on the move- 
ments of the branches of trees, with the ob- 
ject of inquiring into the mechanism of these 
movements. Part of the work had been carried 
out in collaboration with Professor Trow- 
bridge. 
The measuring apparatus, as devised by him, 
consisted of a rod of invar, with four steel 
knobs set on short steel posts fitted into the rod 
near one end, at intervals of ninety degrees, 
and also with one or more small brass blocks 
in the form of square prisms, fitted over the 
rod at some distance from that end. A steel- 
pointed block and a conical steel socket were 
attached to the tree under investigation, and 
a measurement was made by holding one of the 
steel balls in the socket, and making a light 
scratch on the brass plate by gently drawing it 
over the steel point. A careful record was 
kept of the exact position on the brass plate of 
each of the scratches made, and the distances 
between them were measured under the micro- 
scope. In the tests made previous to the tree- 
trunk work, the instrument was found to be 
suitable for general laboratory work as well as 
1C. C. Trowbridge, ‘‘The Thermometric Move 
ments of Tree Branches at Freezing Tempera- 
tures,’’ Bulletin of the Torrey Botanical Club, 43, 
No. 1, pp. 29-56, 1916. 
