OBSERVATIONS. '■ 75 



I think, however, the ohservations are sufficiently accurate to establish the fact that the 

 magnetic force decreases with the altitude, but in what ratio I am unable to say. 

 I have the honor to be, very respectfully, your obedient servant, 



AECH. MacEAE, 



Lieutenant TJ. 8. Navy. 

 Lieut. J. M. G-iLLiss, 



U. 8. Navy, Chief of Expedition. 



TABLE SHOWING THE LATITUDES, LONGITUDES, ELEVATION ABOVE SEA-LEVEL, AND MAGNETIC ELEMENTS AT THE 

 SEVERAL STATIONS BETWEEN SANTIAGO AND MONTEVIDEO. 



From Santiago de Chile to Mendoza and bach by the Uspallata Pass. 



Place. 



South lati- 

 tude. 



West longi- 

 tude. 



Elevation 



above 

 sea-level. 



East decli- 

 nation. 



Inclination. 



Horizontal 



force. 



X. 



Mag. mom't 

 of magnet. 



Total force. 



Santiago 



33 36 25 



70 38 24 



Feet. 

 1,793 



16 27 29 



35 36 40 



6.451385 



0.42105 



7.93540 



Posada de Cliacabuco . 















2,173 













Cuesta de Cliacabuco . 















4,225 













Santa Rosa de los Andes 











32 48 14 



70 40 09 



2,564 













Chacra de Montumas , 











32 46 17 



70 40 33 



2,584 



16 22 14 



35 10 30 



6.49090 



0.42375 



7.94094 



Do do 















2,649 













Mouth of Rio Colorado 















3,454 













Estero de las Cruces , 











32 55 43 



70 24 43 



4,388 



15 55 54 



34 54 30 



6.47505 



0.42255 



7.89574 



Do do 















4,426 













Rio del PeHon . . . 















6,608 













Alto de la Laguna . . 











32 50 56 



70 12 39 



9,207 



15 43 17 



34 51 00 



6.44369 



0.42447 



7.85193 



Do do . . 















9,267 













Casucha de la Cumbre 











32 49 06 



70 09 45 



12,135 



15 39 27 



34 52 30 



6.41623 



0.42666 



7.82243 



Cumbre Pass, North Road 













12,656 













Cumbre Pass, South Road 













12,488 













Casucha de los Puquios . 









32 50 29 



69 57 51 



8,869 



15 14 24 



34 44 00 



6.42626 



0.42605 



7.81960 



Do do 















8,961 













Punta de las Vacas , 











32 53 00 



69 50 51 



7,979 













Tupungato, (Peak) 











33 21 40 



69 50 43 



22,450 













Uspallata .... 











32 34 24 



69 27 19 



6,426 



15 06 26 



34 05 30 



6.40651 



0.42363 



7.73538 



Do .... 















6,350 













El Paramillo . . . 















9,395 













Villavicensio , . .,, 











32 29 37 



69 05 01 



6,501 













Do ... 















5,567 













Mendoza 











S51 15 



68 57 15 



2,497 



15 05 02 



34 22 42 



6.40731 



0.41970 



7.76337 



Do 















2,469 













From Mendoza 



to Santiag 



y and bad 



- 5y the P 



ortillo Pa 



SS. 







Rio de Mendoza 







2,948 













La Arboleda 







3,778 













La Guardia 







6,677 













Los Arenalea 







8,193 













Foot of ! teep ascent of Eastern PortiUo, 

 east side. 







13,331 













Eastern PortiUo Pass 







14,311 













Do do 







14,319 













LaOlIa 







10,350 













Valley of the Tunuyan 







9,521 













Do do 







9,442 













Western PortiUo Pass 







13,189 













Do do 







13,475 













Foot of steep part of descent, west side 







11,184 













San iosi de Chile . 







3,176 













