High rate of speed that could not be any plane

I had just laid down on my hammock and noticed what at first I thought was an incredibly high flying bird, but instantly I realized that it was an object moving dead north at about 10 thousand feet, easy to verify, as it was just below very high ceiling clouds.

I started to track it then, and I started to count off seconds. It was visible moving at such a high rate of speed that it could not be any plane. I estimated how far I could see it before it disappeared, and am sure that it went out of view by the "horizon" about where Watertown, NY, is, which is about 30 miles north of my camp.

It never changed elevation, speed, or course, and was out of sight in about 5 seconds. About 5-10 minutes later, I settled back down when I noticed another similar object moving at exactly the same elevation and course, and I accurately started timing this one and it took 5 seconds plus or minus, before exiting my view.

However, this one changed about 15 times alternating equally spaced from visible to invisible, the objects were clearly below the clouds as it continued on a dead north course. The second object kept disappearing throughout its travels. At first I was simply amazed at how fast and laser-like the trajectory was, but the second one made me feel very uneasy watching a hard, black object disappear and reappear.

source: www.mufon.com