Telegraphic Determinations of Longitude. 1M 
Both parties now returned to Rio, only to find that the cable 
was still broken. In order to be ready for work as soon as it 
should be repaired, Lieut. Com. Green proceeded to Bahia with 
the ship and established a station there, Lieut. Com. Davis with 
his party remaining in Rio. After waiting a month, and there 
still seeming to be no prospect of the repair of the cable, the 
expedition finally sailed for home, arriving at Norfolk, Va., after 
a pleasant and uneventful voyage of forty-five days. Repairs to 
the cable were not completed until several months afterward. In 
May of the next year, the party was again sent out, to complete 
the measurement on the Brazilian Coast, and also to measure from 
Greenwich to Lisbon, the French Bureau of Longitudes having 
failed to carry out its promise to measure from Paris. There 
being no ship available for the purpose the traveling was done by 
mail steamer. Upon arrival in England, an interview was had 
with the Astronomer Royal, who readily agreed to assist in the 
work. Lieut. Com. Green accordingly established his observatory 
at the landing place of the cable at Portheurnow in Cornwall, 
and Lieut. Com. Davis proceeded to Lisbon and occupied the 
station used there the year before. Owing to the foggy and 
rainy weather prevalent in England at that season, it was found 
impossible to make any astronomical observations at the Porth- 
curnow observatory. The work was therefore done in this way:— 
Observations were made at Greenwich and at Lisbon, and Porth- 
eurnow and Carcavellos were used as transmitting stations. The 
chronometer at Porthcurnow was compared automatically with 
the clock at Greenwich, and by cable with the chronometer at 
Carcavellos. The latter was compared automatically with that at 
Lisbon, before and after the cable exchange. At this time there 
were made at Carcavellos, some experiments with a view to mak- 
ing the receipt of the time signals over the cable automatic, thus 
doing away with the personal equation of the receiver. The 
instrument in use for the regular business of the cable was what 
is known as the siphon recorder, also the invention of Sir Wm. 
Thompson. In this a small coil of fine wire is suspended by a 
fibre of silk, between the poles of a powerful permanent magnet. 
The currents from the cable pass through this coil and the action 
is to deflect it to the right or left, just as the mirror is deflected 
in the instrument already described. Attached to this coil is a 
siphon made of a capillary glass tube. One end of the siphon 
dips into a reservoir of aniline ink, and the other hangs immedi- 
