VOL. XV.] PHILOSOPHtCAL TRANSACTIONS. 245 



and let through the upper room into this vessel, and reaching almost down to 

 the floor E F. V W, a pipe open above and below, and let into the upper room. 

 These pipes must be close joined round about them, to the floors C D and 

 G H, X, Y are two little hemispherical bladders, prepared with oil or some oily 

 substance, against water, and cemented with their mouths upward to the floor 

 E F underneath, a, (3, two valves, opening out of the upper room into the 

 bladders, y, S, two other valves opening out of the bladders into the inner 

 vessel above. N Z, a pendulum playing on the centre N, and having two battle- 

 door arms a, b, to squeeze alternately the bladders which rest upon them. 



Let the upper room be filled with water at the pipe VW, and if the pen- 

 dulum be made to play by clock-work, the bladders will perpetually pump it 

 thence into the inner vessel, and the compressed air G I K H in the upper part 

 of that vessel, pressing on the surface of the water I K, will force it thence 

 into the pipes O Q, PR, out of which spouting with a perpetual even stream 

 into the spoons S, T, it will run down by the pipe W V, into the upper room 

 again. The pendulum will play most easily when the upp>er room is filled to the 

 top of the pipe WV. Instead of the bladders, may be other contrivances, as 

 of suckers or little organ bellows, playing alternately with two leaves about an 

 axis in the middle. Sept. 1 6, l685. 



^ Total Eclipse of the Moon, ^nno l685, Dec. 10, N.S. observed at Dantzic, 

 by M. Hevelitis. Abridged from the Latin. N° 178, p. 1256. 



It required no small skill and labour to manage our tubes, though they were 

 but short, viz. of 5, 6, and 7 feet, and to keep them sufficiently steady to the 

 moon, to distinguish exactly the penumbra, and mark out all the phases, 

 through what spots they passed, or what part they arrived at in every particular 

 instant of time. These things I have performed as well as I was able, and as 

 the severe season and floating clouds would permit. It may be observed that a 

 very dense penumbra preceded the true eclipse, so that I could scarcely, if at 

 all, distinguish the precise beginning. As to the colour, it is particularly 

 remarkable in this eclipse ; for I have very rarely found so great a diversity in 

 colour. Sometimes it was rusty, or of the colour of a weasel, but when the 

 total obscuration came on, the moon's limb was in parts rather livid, and partly 

 brightish and ruddy. But in the middle of the moon appeared an obscure and 

 dense little cloud, so that we could not well distinguish the moon's spots. 

 This dark cloud advanced gradually towards the right hand, and to the Palus 

 Maeotis; so that about the beginning of the recovery of light, the whole true 

 shadow appeared very black, and about the last phasis noticed, the remaining 



