Unit tests will no longer be counted in the computation of grades for the Summer School's Physics S-1 as the result of the disappearance of a unit test solution booklet from the Science Center last Wednesday, the head of the course announced yesterday.

Don Chodrow, assistant professor of Physics at Northern Michigan University, also announced that students in the course will have until 4 p.m. today to withdraw from S-1. The registrar's office extended the deadline from last Friday to accomodate students who do not want to continue the course now that it is no longer on a self-paced basis.

Under the revised grading policy the final examination will count for 25 per cent of the final grade, while the mid-term this Friday will count 15 per cent. The remaining 60 per cent of the grade will be based on work done in laboratory, seminars and lecture units.

Originally there was no mid-term and the final could only raise or lower a student's grade one increment.

Chodrow said yesterday he arrived at the new formula for grades after meeting with Physics S-1 students Friday and consulting with H. Francois Wilkinson, associate director of the Summer School.

The meeting with students aroused "no great enthusiasm" for more hourlies instead of the three-hour mid-term, according to Chodrow.

He said the Harvard Police have not contacted him about the progress of its investigation into last Wednesday's incident. "I'd be curious to know who did it," Chodrow added.

The officer in charge of the investigation was unavailable for comment yesterday.