74 



SCIENCE 



[N. S. Vol. XXXI. No. 785 



ocean magnetic work is now on a stage of 

 perfection not hitherto reached, permitting 

 obtaining useful data not only expeditiously 

 but also with all necessary accuracy both as 

 regards practical and scientific demands. 



The introduction of circular observatories 

 in which the magnetic instruments are 

 mounted has proved of great advantage. The 

 domes being revolvable, it is possible to direct 

 an open panel to any part of the skies, thus 

 permitting astronomical and magnetic obser- 

 vations being made with full protection to the 

 observer and the instrument from wind and 

 weather. Hitherto all such observations have 

 had to be made on an open bridge. 



Another important feature of the research 

 work on this unique vessel is the developing 

 and perfecting of a producer gas engine for 

 auxiliary marine propulsion. The Carnegie 

 has a non-magnetic plant of this kind of 150 

 horse power, sufficient to drive her at six 

 knots in -calm weather, or at about 144 knots 

 per day at a total cost for coal consumed dur- 

 ing the day of but seven dollars. Such diffi- 

 culties as have been encountered thus far are 

 mainly due to the non-magnetic metals which 

 have had to be so largely employed. How- 

 ever, these difficulties are being successfully 

 solved one by one. As a matter of fact, the 

 Carnegie has entered and left every port thus 

 far, under bare poles, with the aid of her 

 auxiliary power and so likewise the vessel was 

 swung during the trial tests at Gardiner's 

 Bay and Falmouth, using only the auxiliary 

 power. This vessel is the first sea-going one 

 having such a plant. 



The next table gives the results of the mag- 

 netic observations up to Falmouth. 



The last three columns show the average 

 errors of the best magnetic charts at present 

 available. Glancing over them the following 

 conclusions may be drawn : 



1. From Long Island to some point off New- 

 foundland the charts used by mariners show 

 too small westerly magnetic declinations (va- 

 riations of the compass) by about one degree 

 in the maximum, thereafter and continuing 

 to England, the error changes sign, indicating 

 that the charts give too large west magnetic 



declination, the maximum error being nearly 

 one degree. Were there not such " a syste- 

 matic run in the errors they would not be of 

 great importance to navigation, but as the 

 sign is the same for great distances the gen- 

 eral effect would be, in the present instance. 



Magnetic Results obtained on the 



Septemler-Octoher 18, 1909, in the 

 Atlantic Ocean 



No. 1 at Gardiner's Bay; No. 14 at St. Johns, 

 N. P.; No. 32 in Falmouth Bay, England. 



to set the course of a vessel (when reliance 

 must be put solely upon the compass and the 

 log) always towards Newfoundland, whether 

 the vessel came from the east or the west. 



2. The chart errors in dip may amount to 

 one haK degree. 



3. The chart values of the horizontal inten- 

 sity are in general too low, the error amount- 

 ing at times to nearly one tenth part. 



4. A part of the errors found in the three 

 magnetic elements are due to secular varia- 

 tion. 



