As he often did, Orson Pratt this May 11, 1847 went out ahead of the main body of pioneers, his carriage loaded with these scientific instruments, now on display in a Salt Lake City museum.

Here where the North Platte airport now sits, Pratt used his instruments and the sun to calculate the location of the pioneers.

Orson Pratt:

"A MERIDIAN OBSERVATION OF THE SUN GAVE FOR THE LATITUDE 41 DEGREES 7 MINUTES 44 SECONDS. WE ARE A FEW MILES ABOVE THE JUNCTION OF THE NORTH AND SOUTH FORKS OF THE NEBRASKA OR PLATTE."

The pioneers ended their day's journey a half mile from Pratt's scientific station. Only eight miles this day. Because of so little feed, the animals pulling the wagons were very weak.