The Helium Murder(39)

I didn’t relish the thought of being a prisoner in my own home, but the idea of venturing out into the mortuary building, dark and empty all around me, was even more unappealing. Tomorrow was soon enough for Frances Whitestone’s telephone number, anyway, I reasoned, and I had a freezer full of gourmet ice cream to ease the pain of my captive status.

One more reading of the unsettling note satisfied me that I wasn’t in immediate danger, certainly nothing to warrant a call to Matt. I did, however, wish that there could be a cruiser outside my house on a permanent basis.

I took a bowl of Cherry Garcia ice cream and a mug of coffee to my computer. I had some finishing touches to add to my presentation for Peter’s class, assuming he was still talking to me. It seemed months since the dramatic flop I’d produced and directed in his faculty lounge, but it was less than twelve hours ago, I realized.

As usual, I found respite from the emotional highs and lows of the week in science. Although it wasn’t news to me, I marveled again at the feat of Guglielmo Marconi, successfully transmitting a signal using radio waves when he was only twenty-one years old.

The outline I’d handed to Peter in draft form still needed attention and I began to fill in a few lines summarizing the contributions of each of the six other scientists on my list. Working alphabetically, a pile of scientific biographies on my lap, I started with a few sentences about the short but brilliant career of Maria Agnesi.

The oldest of twenty-one children, Maria spoke many languages and, at the age of seventeen, wrote a commentary on conic sections. At twenty, she published a volume of one hundred and ninety essays on philosophy, logic, mechanics, and Newton’s theory of universal gravitation. Among the essays was a plea for the education of women. I hoped that Peter’s students, in the same age range as both Marconi and Agnesi when they did their ground-breaking work, would be inspired.

For the most part, I was comfortable working at my computer, but every now and then I’d hear a noise and feel a twinge of panic. At least three times I tracked down sounds that ended up as refrigerator noise, ice falling from the roof, and steam from the radiator in my bedroom.

I decided to write one more summary, on Avogadro, and then call Elaine in Berkeley, to hear a friendly voice.

Avogadro, unlike the two well-respected child geniuses, received little acceptance as a scientist during his lifetime, but became famous after his death when people realized the importance of his hypotheses. Almost everyone who’d had even an elementary chemistry class knew “Avogadro’s number,” 602,600,000,000,000,000,000,000, also written, 6.026 × 1023, the number of particles in a mole of gas.

To give the students an idea of how big Avogadro’s number was, I used the standard analogy: if you could count one hundred particles every minute, and counted twelve hours every day and had every person on earth also counting, it would still take more than four million years to count a mole of anything.

A mole of anything. A mole! I came close to shouting “Eureka!” when it hit me. Margaret Hurley had minored in chemistry in college. She would have known Avogadro’s number by heart. Even I did, and I’d had only two chemistry classes in my life. I couldn’t believe it wasn’t the first thing that came to me when I heard “mole.” I’ve been retired too long, I thought.

I stood up and paced, back and forth from my computer to my window, recreating the crime scene in my mind. What if Hurley had seen the license plate of the car that was coming toward her, and read 6026 or even 602623, the number including the power of ten? She would have recognized it immediately and made the connection with a mole. One word, mole, was certainly easier to say to the paramedic than the six digits she’d seen.

One problem stood out, however—Massachusetts license plates didn’t have four or six digits; they had three digits and three letters. I thought of other possibilities, like an out-of-state car, or a Massachusetts plate with 602, the first part of Avogadro’s number, and any three letters. I wondered how to approach Matt on the research that would have to be done to check out my hypothesis. I hoped I wouldn’t follow in Avogadro’s footsteps and have my theories win acclaim only after my death.

My excitement at determining what I saw as the connection between Margaret Hurley’s “mole” and her murderer took over, and my anxiety at the near-ultimatum I’d received on my doorstep all but disappeared. I wanted to share my discovery, but hadn’t worked out my strategy for telling Matt. Technically, he’d fired me, I remembered with dismay. Calling Peter was out of the question, and I’d already disturbed Rose sufficiently. It occurred to me that my circle of friends in the Commonwealth of Massachusetts was pitifully small.